Term
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Definition
| disease process characterized by excessive cellular proliferation leading to a cell mass or tumor |
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Term
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Definition
| a neoplasm that has become malignant (capable of invading neighboring tissues) |
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Term
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Definition
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Term
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Definition
| when a cancer spreads to a distant site within the body |
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Term
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Definition
| cancer of mesenchymal origin such as bone, connective tissue or muscle |
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Term
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Definition
| cancer of epithelial origin |
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Term
| hematopoietic and lymphoid malignancies |
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Definition
| cancer of RBC and WBC progenitors |
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Term
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Definition
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Term
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Definition
| cancer of embryonic cells. can consist of several types of differentiated tissues. most common is mesenchymal origin. |
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Term
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Definition
| genes that when mutated have altered function resulting in abnormal stimulation in cell division and proliferation |
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Term
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Definition
| nonmutated oncogene promoting cell proliferation in a specific tissue |
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Term
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Definition
| increased activity of proto-oncogene (mutated) |
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Term
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Definition
| mutation in only one allele enough to change phenotype of cell |
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Term
| mutation in coding region |
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Definition
| oncogene product overly active or no longer under normal molecular control |
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Term
| mutation in upstream regulatory element |
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Definition
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Term
| amplification of genomic number |
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Definition
| detected in karyotypes as homogenous staining regions in chromosomes or as double minutes |
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Term
| mutation via chromosomal rearrangement |
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Definition
| can change upstream regulation or form chimeric protein that acts as an oncogene; The Philidelphia chromosome translocation |
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Term
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Definition
| proto-oncogene inadvertently incorporated by a virus, mutated, and then inserted into human chromosome |
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Term
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Definition
| growth factors, growth factor receptors, intracellylar secondary messengers such as G-proteins and kinases, gene regulatory proteins, telomerase, antiapoptotic proteins, cell cycle factors |
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Term
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Definition
| contribute to oncogenecity through loss of function (must lose both alleles in a cell) |
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Term
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Definition
| individuals who are heterozygous for the loss of a tumor suppressor gene lose their sole functional copy of the gene leading to cancer |
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Term
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Definition
| enzyme required to replicate ends of DNA, shortening may partially act as an aging mechanism in cells,most cancers have this |
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Term
| Philadelphia chromosome translocation |
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Definition
| A derivative of chromosome 22, which has exchanged part of its long arm for a segment of material from chromosome 9q that contains the ABL oncogene. Formation of the chimeric BCR-ABL gene is the critical genetic event in the development of chronic myelogenous leukemia |
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Term
| translocation break points |
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Definition
| originally used to map loci of oncogenes |
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Term
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Definition
| oncogene activation or loss of tumor suppressor genes |
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Term
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Definition
| early event in many cancers leading to expression of normally silent allele which converts proto-oncogene to cellular oncogene |
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Term
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Definition
| can lead to silencing of a tumor suppressor gene |
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Term
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Definition
| target proteins only needed in rapidly dividing cells |
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Term
| non-malignat cells of body that are also rapidly dividing |
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Definition
| skin, hair, GI tract, RBC precursors, immune cells, etc |
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Term
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Definition
| inhibits dihydrofolate reductase to target rapidly dividing cells |
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Term
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Definition
| mechanism of resistance to chemotherapy |
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Term
| resistance to methotrexate |
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Definition
| amplification of the dihydrofolate reductase gene |
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Term
| amplification of a membrane protein gene |
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Definition
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Term
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Definition
| increase incidence of disease of selected allele |
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Term
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Definition
| the tendency to marry based on shared characteristics |
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Term
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Definition
| marrying of blood relatives |
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Term
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Definition
| allelic frequency should decrease |
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Term
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Definition
| carriers may have increased fitness against certain pathogenic conditions, which will increase allelic frequency. ex - sickle cell carriers and cystic fibrosis carriers are more resistant to cholera |
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Term
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Definition
| changes in allelic frequency significantly vary generation to generation |
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Term
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Definition
| when all individuals of a population are descended from a relatively small number of ancestors, one of whom had a rare allele. ex - polydactly among Amish groups, albinism among Hopi indians, variegate porphyria from Afrikaners of South Africa |
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Term
| indications for genetic prenatal diagnosis |
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Definition
| maternal age 35 or greater; previous child with a de novo mutation; presence of a structural abnormality in a parent; family history of a genetic disorder that can be detected by biochemical or DNA analysis; maternal serum or ultrasound detects possibility of chromosomal disorder in low risk mothers |
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Term
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Definition
| syringe inserted through abdominal wall to remove sample of amniotic fluid; there isn't enough amniotic fluid until week 16; cells are isolated and cultured; fluid itself can be analyzed |
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Term
| chorionic villus sampling |
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Definition
| biopsy needle inserted through abdominal wall or through vagina to obtain sample of chorionic villus; can be performed during weeks 10-12; rapid rate of cell division so you are able to perform a karyotype without culturing cells |
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Term
| Percutaneous umbilical cord blood sampling |
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Definition
| allows culturing of fetal WBCs which can be cultured faster and easier than epithelial cells obtained by amniocentesis; can be performed after week 20 |
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Term
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Definition
| population based method for identifying persons with certain genotypes known to be associated with a genetic disease or predisposition to a genetic disease. differs from genetic testing due to size of population involved |
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Term
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Definition
| prototype neonatal screening program. |
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Term
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Definition
| only disease where adult screening is proposed; it is an autosomal recessive disorder affecting 3/1000 in US; iron overload leading to permanent organ damage; successfully treated by phlebotomy; can test with iron-transferrin levels or molecular test |
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Term
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Definition
| tests for healthy individuals who are at risk for having affected children |
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Term
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Definition
| among Jews of eastern European descent; successfully reduced by genetic screening |
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Term
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Definition
| in Cyprus; successful reduction of incidence through heterozygout screening |
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Term
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Definition
| in African Americas; no decrease in incidence due to genetic screening |
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Term
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Definition
| in Caucasian Americans; proposed that we test for heterogeneity; but there are several recessive alleles that cause it, which makes testing more expensive or insensitive |
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Term
| standard prenatal screening |
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Definition
| serum alpha-fetoprotein and karyotyping with advanced maternal age |
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Term
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Definition
| deals with the influence of genetic variation on drug response in patients by correlating gene expression wiht a drug's efficacy or toxicity. |
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Term
| most common focus of pharmacogenetics |
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Definition
| drug.cell interaction (efficacy) and breakdown (side effects) |
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Term
| bimodal or trimodal distribution of drug responses |
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Definition
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Term
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Definition
| under control of many genes |
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Term
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Definition
| anticoagulant drug; metabolized by cytochrom P450; two mutant alleles within the population produce highly reduced metabolism, so these individuals require lower dose to prevent unwanted bleeding |
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Term
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Definition
| reverse transcriptase inhibitor used to treat HIV; 5% of patients demonstrate fatal hypersensitivity; responsible gene not yet determined |
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Term
| single nucleotide polymorphisms (SNPs) |
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Definition
| 1/1000 bases within human genome demonstrate variation with most being bi-allelic |
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Term
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Definition
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Term
| computer analysis of microarrays |
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Definition
| determination of which SNP correlates to patients who are hypersensitive/do not respond to a particular drug |
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Term
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Definition
| a technique for correcting defective genes responsible for disease development |
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Term
| most common approach to gene therapy |
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Definition
| normal gene inserted into genome to replace a nonfunctional gene |
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Term
| other approaches to gene therapy |
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Definition
| mutated gene exchanged for a wild type gene through homologous recombination; mutated gene repaired through selective reverse mutation; regulation of a particular gene altered; inhibit translation of mutant gene |
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Term
| in vivo delivery of gene therapy |
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Definition
| inject cloned gene into person |
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Term
| ex vivo delivery of gene therapy |
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Definition
| take patient's cells from them, grow and culture with cloned gene of interest, then return to patient |
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Term
| viral vector delivery of gene therapy |
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Definition
| virus inserts genome into host genome; can be used to insert gene of interest |
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Term
| non viral vectors for delivery of gene therapy |
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Definition
| naked DNA, liposome, receptor mediated endocytosis, stem cell therapy |
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Term
| liposome-mediated gene therapy |
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Definition
| add DNA of interest to liposome, insert liposome into human cell, it goes to nucleus and results in the tranlation of this gene |
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Term
| embryonic stem cells for gene therapy |
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Definition
| transfer normal gene or correct mutation in vitro to a culture of patient's cells; insert the patient's corrected nucleus into a donor egg; allow egg to develop into blastocyst; culture genetically corrected autologous stem cells for transplantation; insert into patient |
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Term
| challenges to overcome to liscence gene therapy in US |
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Definition
| improve gene transfer efficiency (particularly for non-viral vectors), new DNA must be incorporated into chromosome to insure long-term function, site specific incorporation to avoid insertioal mutagenesis, immune response/toxicity issues |
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Term
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Definition
| period of development from fertilization to birth |
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Term
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Definition
| period of development from fertilization to the end of week 8 |
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Term
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Definition
| period of development from the beginning of the 9th week until birth |
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Term
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Definition
| cell numbers increase by dividing (mitosis) causing growth and an increase in size |
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Term
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Definition
| cells are often produced in one region of the body then move to their final destination |
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Term
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Definition
| cells convert from a general non specific form into a more mature cell type of function |
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Term
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Definition
| cells play with their neighbors through contact or chemical cues to initiate migration and differentiation |
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Term
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Definition
| programmed cell death; normal planned death of cells to shape or sculpt anatomic structures |
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Term
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Definition
| are present on the surface of cells. they span the plasma membrane and respond to changes in extracellular environment by altering gene expression |
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Term
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Definition
| span the plasma membrane. internally bind to cytoskeleton and externally binds to other cells or the ECM. they allow attachement to adjacent cells and facilitates guided cell migration along specified paths |
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Term
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Definition
| released by cells into the surrounding fluid. can act on adjascent cells or through concentration gradients across a distance to control cell growth and differentiation. |
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Term
| Fibroblast Growth Factor (FGF) |
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Definition
| regulates blood vessels, limb, brain, and axon growth |
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Term
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Definition
| regulates nervous system, gut and limb, regional patterning |
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Term
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Definition
| regulates limb, brain, and urogenital differentiation |
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Term
| Transforming growth factor B (TGFB) |
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Definition
| regulates cell division, cell migration, cell death |
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Term
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Definition
| malformation from excessive cell division |
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Term
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Definition
| malformation from insufficient cell migration into the developing upper lip tissue |
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Term
| Polydactyly (webbed fingers) |
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Definition
| maformation from incomplete apoptosis |
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Term
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Definition
| if rotation of the palate shelves happens either too early or two late, the shelves do not fuse |
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Term
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Definition
| a compound or agent that disrupts embryonic or fetal development |
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Term
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Definition
| when an organ system is sensitive to the effects of a particular teratogen. occurs during organ formation or during a vital maturational step. |
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Term
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Definition
| consists of cytoplasm, 2 haploid nuclei, cell membrane, and zona pellucida |
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Term
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Definition
| glycoprotein layer that acts as a protective shell around fertilized egg through late blastocyst stage |
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Term
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Definition
| when the male and female nuclei combine and the cell begins to divide |
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Term
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Definition
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Term
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Definition
| early embryonic cells, still enclosed in zona pellucida |
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Term
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Definition
| blastomeres up to the 8-cell stage retain the ability to develop into a complete embryo. identical twins result in one of these blastomeres separates off or the zygote splits |
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Term
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Definition
| 16 cell stage. tightly compacted. 3-4 days after fertilization |
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Term
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Definition
| cells at the center of the morula and will become the embryo proper |
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Term
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Definition
| cells at the periphery of the morula and will become the trophoblast |
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Term
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Definition
| the precursor of the placenta |
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Term
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Definition
| zona pellucida begins to disentigrate 5-6 days after fertilization. fluid comes into the morula through the disintegrating zona pelucida and forms a fluid filled cavity. attaches to uterine wall around day 7 |
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Term
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Definition
| first fluid filled cavity |
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Term
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Definition
| outer cell mass is now one layer thick around the outside of the blastocoel cavity and will go on to form the placenta |
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Term
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Definition
| inner cell mass is pushed to one side as the blastocoel forms |
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Term
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Definition
| the side of the blastocyst with the embryoblast. this is always the side that attaches to the endometrium. |
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Term
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Definition
| where fertilization takes place and then the zygote divides |
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Term
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Definition
| process by which the blastocyst attaches and becomes embedded in the uterus. begins 6-7th day and continues til day 10. |
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Term
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Definition
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Term
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Definition
| when the trophoblast at the embryonic pole contacts the endometrium; they produce compounds that erode the uterine endometrium and allow them to grow into the endometrium. they continue to divide and their cell membranes fuse to form a continuos multinucleated mass with no internal cell boundaries. as it enlarges, the blastocyst is drawn deeper into the endometrium.eventually surrounds entire blastocyst. |
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Term
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Definition
| remaining cells of the trophoblast surrounding the blastocystic cavity and the embryoblast. they form a distinct layer between the embryoblast and the differentiated syncytiotrophoblast. as the blastocyst is pulled further into the endometrium, more of it comes into contact with endomedium and differentiates into syncytiotrophoblast. after the blastocyst is fully implanted, these cells remain as a layer around the blastocoel and over the embryoblast. |
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Term
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Definition
| in the syncytiotrophoblast, cavities that join with eroded maternal arteries and veins to supply the developing embryo with oxygen and nutrients and allow for removal of CO2 and metabolic wastes. blood must cross the cytotrophoblast to get to the embryo. |
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Term
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Definition
| extensions of the cytotrophoblast into the syncytiotrophoblast. as they grow, they protrude into the lacunar network where they are bathed by maternal blood, then over time they branch and are supplied with blood vessels from the embryo. fetal blood does not mix with maternal blood. this increases the fetal vasculature surface area. |
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Term
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Definition
| normal site of implantation |
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Term
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Definition
| implantation occurs outside the uterine body. the inelastic uterine tube ruptures by the 8th week causing embryonic death and maternal hemorrhage. usually occurs due to scaring of hte uterine tube by STDs or PID. |
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Term
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Definition
| 95% of ectopic implantations. regions along uterine tube |
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Term
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Definition
| causes 40% of all female infertilities |
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Term
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Definition
| finger-like projections off infundibulum. if the egg is fertilized here, it may implant on the ovary or in the abdominal cavity. |
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Term
| Rectouterine pouch and mesentaries |
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Definition
| areas where abdominal pregnancies often occur |
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Term
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Definition
| layer of embryoblast cells located on the border between it and the blastocoel |
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Term
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Definition
| remaining embryoblast cells after hypoblast has differentiated |
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Term
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Definition
| cavity formed within the mass of epiblast cells. it enlarges, spreading the epibast into a single layer of cells around the cavity |
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Term
| amnion or amniotic membrane |
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Definition
| epiblast cells comprising the arch of the dome that become thin |
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Term
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Definition
| the thick epiblast layer at the base of the dome and the hypoblast layer. these form the embryo |
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Term
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Definition
| cells from the marginal edge of hte hypoblast disc grow over the cells of hte cytotrophoblast forming a lining in the blastocoel |
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Term
| primary yolk sac or primary umbilical vesicle |
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Definition
| blastocoel is now called this once the exocoloemic membrane grows down over the cytotrophoblasts |
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Term
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Definition
| layer of cells derived from the excocoelomic membrane that forms between it and the cytotrophoblast. it grows around the outside of the exocoelomic cavity, the epiblast, and the amniotic cavity |
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Term
| chorionic cavity or extraembryonic coelomic cavity |
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Definition
| spaces begin to form in the new extraembryonic mesoderm layer and they coalesce into a continuous cavity. it splits the extraembryonic mesoderm into two distinct sheets |
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Term
| extraembryonic somatic mesoderm |
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Definition
| lines the cytotrophoblast cells on the outside of the chorionic cavity and covering the amniotic membrane |
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Term
| extraembryonic visceral mesoderm |
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Definition
| covers the primary yolk sac |
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Term
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Definition
| outer wall of the choronic cavity. consists of extraembryonic somatic mesoderm covered by cytotrophoblast cells, and outside this is the syncytiotrophoblast cells embedded in the uterus. will later go on to form the placenta. |
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Term
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Definition
| inside the chorionic cavity are the amnion and the embryonic disc covered by extraembryonic somatic mesoderm. these are connected to the chorion by this structure which is made up of a thick band of extraembryonic somatic mesoderm. it will eventually develop blood vessels and become the umbilicus. |
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Term
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Definition
| attached to the embryonic disk and covered by extraembryonic visceral mesoderm. as the chorionic cavity enlarges, a portion of this pinches off leaving a much smaller one. |
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Term
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Definition
| when the pregnancy can be detected. the large chorionic cavity can be observed by an ultrasound.hu |
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Term
| human chorionic gonadotropic (hCG) |
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Definition
| hormone produced by syncytiotrophoblasts. it is taken up by the mother's blood and can be detected in blood and urine 2 weeks after conception. |
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Term
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Definition
| size of embryo at 2 weeks |
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Term
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Definition
| the most important developmental event. the process by which the embryo develops from a bilaminar disc into a trilaminar disc. cells at one end of the epiblast divide and migrate to the midline. they form a ridge of cells that buckles inward to form a groove on the surface of the epiblast. migrating cells move toward midline and flow down through the groove toward the hypoblast. |
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Term
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Definition
| where the migrating epiblasts move to the midline and move down into it. its located at the center on the surface of the epiblast. |
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Term
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Definition
| at the front end of the primitive groove; where the groove is enlarged |
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Term
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Definition
| the tissue ridge around the primitive pit that is higher |
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Term
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Definition
| the primitive groove, primitive pit, and primitive node together are called this |
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Term
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Definition
| established during gastrulation. as the cells differentiate, they lose the ability to form a variety of cell types, the range of cells and tissues they can now become is more limited |
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Term
| throughout the 3rd week and tapers off late in the 4th week |
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Definition
| time frame of gastrulation. the end is marked by the disappearance of the primitive streak. |
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Term
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Definition
| almost always lethal, causing fetal or neonatal death due to severe malformation |
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Term
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Definition
| the primitive streak persists. this is a solid or fluid filled tumor at the site of the primitive streak. seen most often in newborn females. |
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Term
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Definition
| the three distinct layers of the trilaminar embryo. endoderm, mesoderm, ectoderm. |
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Term
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Definition
| the first cells through the primitive groove and replace the hypoblast |
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Term
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Definition
| second cells migrate through the primitive streak to form a layer between the endoderm and the epiblast |
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Term
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Definition
| cells remaining in the epiblast after migration. give rise to the skin, nervous system, neural crest tissue, and many structures of the head and face |
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Term
| precordal plate or oropharyngeal membrane |
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Definition
| at the cranial end, there is a small circular region where ectoderm is directly adherent with the endoderm. this region will later become the mouth. |
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Term
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Definition
| at the caudal end, there is a small circular area of adherent ectoderm and endoderm. this will later become the anus. |
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Term
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Definition
| marks the first indication of body axis. this identifies the dorsal-ventral axis of the embryo. dorsal has the embryoblast, ventral has the blastocoel |
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Term
| formation of the primitive streak in the bilaminar disk |
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Definition
| indicates the cranial-caudal axis |
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Term
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Definition
| some of the mesoderm cells directly under the primitive node intercalate (mix with) the endoderm layer and these cells begin to form a cord in the midline in the endoderm layer. the cells grow cranially and form this structure on the ventral surface of the trilaminar disk |
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Term
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Definition
| cells proliferate along the notochordal plate and infolds into a tube. this becomes detached from the endoderm during infolding leaving a continuous layer of endoderm. it induces surrounding tissue to differentiate |
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Term
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Definition
| notochord causes the overlying ectoderm to differentiate into this. it is a thickening of the ectoderm that will become the nervous system. |
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Term
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Definition
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Term
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Definition
| further from the notochord |
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Term
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Definition
| furthest from the notochord and continuous with the extraembryonic mesoderm |
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Term
| nucleus pulpossus of intervertebral disks |
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Definition
| what the notochord becomes later in development |
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Term
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Definition
| cluster of mesoderm cranial to the prechordal plate which will become the future heart |
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Term
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Definition
| formation of the nervous system |
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Term
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Definition
| by the middle of the 3rd week, the notochord is growing cranially and has induced the overlying ectoderm to differentiate into neuroectoderm which is thicker |
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Term
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Definition
| cells at the lateral edge of hte neural plate proliferate, this causes the lateral edges of the neural plate to elevate into neural folds, the neural folds bend toward each other at the midline, the neural folds fuse together forming a hollow neural tube running the length of the embryo, the neural tube detaches and a continuoys layer of ectoderm grows to cover the tube |
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Term
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Definition
| fusion of the neural plates begins in the cervical region, moving cranial and caudally like a zipper to form the nerual tube. the neural tube is open to the amniotic cavity at both ends. the cranial end closes around day 25. the caudal end closes around day 28. what are these openings called? |
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Term
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Definition
| the cranial neural tube expands to form this |
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Term
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Definition
| the caudal portion of the neural tube becomes this |
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Term
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Definition
| the lumen of the cranial neural tube will become this |
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Term
|
Definition
| the lumen of the caudal tube forms this |
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Term
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Definition
| where the cranial tube does not close and the underlying nervous tissue is only partially formed and is exposed |
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Term
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Definition
| when the spinal canal does not close and the underlying nervous tissue is only partially formed and is exposed |
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Term
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Definition
| incomplete closure of the spinal cord where there is no visible lesion but a defect in vertebral arch formation can be seen on radiographs |
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Term
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Definition
| originates in the ectoderm along the lateral edge of the neural plate. forms in the elevating neural fold. as the neural fold elevates, these cells proliferate and move into the mesoderm forming a flattened cluster of cells in between the neural tube and overlying ectoderm. it then separates and moves to lie laterally on either side of the neural tube before migrating throughout the body |
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Term
| intraembryonic coelom or body cavity |
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Definition
| lateral mesoderm splits into two layers, both of which are continuous with the extraembryonic mesoderm. the space between these layers is called what? |
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Term
|
Definition
| paraxial mesoderm forms this |
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Term
| structures associated with the urogenital tract |
|
Definition
| intermediate mesoderm forms this |
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Term
| parietal or somatic mesoderm |
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Definition
| one of the layers that splits from lateral plate mesoderm. it forms the dermis of the back, abdomical wall and limbs, and the serosal linings of the body cavities |
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Term
| visceral or splanchnic mesoderm |
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Definition
| one of the layers that splits from lateral plate mesoderm. it is continuous with extraembryonic mesoderm covering the yolk sac. it forms the muscular layers of the gut, blood vessels, and the serosal covering on each organ |
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Term
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Definition
| paired blocks of paraxial mesoderm form in a segmented manner on either side of the developing neural tube. form from cranial to caudal, staring on day 20 (end of 3rd week) and continuing to the end of the 5th week. there are 42-44 pairs. so regular that it can be used to age the embryo. caused by cyclic expression of notch, WNT, and FGF families. this mesoderm will later form much of the skeleton, body wall, and limbs. each one forms an association of nerve, muscle, and skin that remain linked throughout life |
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Term
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Definition
| originates from cells in the ventromedial portion of the somite. will become the vertebra and ribs |
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Term
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Definition
| originates from the cells in the lateral portion of the somite. will form the dermis of the back and limbs |
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Term
|
Definition
| originates from cells dorsomedial and ventrolateral to the dermatome. these cells migrate under the dermatome and join in a single layer. will form the muscles of the back and limbs and body wall |
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Term
|
Definition
| the basic human structure is a hollow tubular form. development of the embryo from a flat disk into a hollow tube requires a shape change. happens in both the cranial-caudal and the lateral directions. results from unequal proliferation of cells on the upper surface of the embryonic disk. the upper layer grows faster which bends the embryo towards the lower surface of the disk. begins late in the 3rd week and continues throughout the 4th week |
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Term
|
Definition
| two sharp folds form, one at the cranial end and the other at the caudal end. they result mainly from the elongation and growth of the nervous system in the craniocaudal direction |
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Term
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Definition
| folding in the head region causes this region to move from a cranial position to a caudal position relative to the oropharyengeal membrane (mouth) and ventral to the foregut |
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Term
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Definition
| folding creates this. as the cranial disc folds under, a pouch is created lined with endoderm. the pouch ends blindly with the oropharyngeal membrane. this membrane will eventually break down to form the mouth opening. |
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Term
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Definition
| folding in this region causes the primitive strek which was cranial to the cloacal membrane (anus) to become caudal. if the primitive streak does not regress, remnants of the streak may become a sacrococcygial teratoma and will be located posterior to the anus |
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Term
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Definition
| folding creates this. an endodermal lined pouch is created in the caudal embryo terminating with the cloacal membrane which will later break down to form the anus and openings to the reproductive and urinary tracts |
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Term
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Definition
| an early fetal membrane projecting into the connecting stalk, becomes incorporated into the embryo proper. it now comes off the newly formed hindgut and will later form part of the urinary system. |
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Term
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Definition
| result from frapid growth of the somites and vertebra. will later become the abdominal walls. folding causes the opening into the yolk sac to decrease in size forming an amnion covered stalk that will later develop into the umbilical cord |
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Term
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Definition
| the early heart develops in the 3rd week from these in the cardiogenic region |
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Term
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Definition
| late in the 3rd week, endocardial tubes develop into this. it joins with newly formed blood vessels to create the primordial cardiovascular system. |
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Term
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Definition
| blood begins to circulate and the heart beat is visible by ultrasound. |
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Term
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Definition
| first organ system to become functional in the embryo |
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Term
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Definition
| the formatio of new vessels by the aggregation of angioblasts into clusters called blood islands. cavities appear in the blood islands. the angioblasts flatten and diffeentiate into endothelial cells which line the new vessel. |
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Term
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Definition
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Term
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Definition
| clusters of angioblasts. they coalesce to form the major blood vessels |
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Term
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Definition
| new vessels sprout off preexisting vessels. this allows the cardiovascular system to expand as the embryo grows. |
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Term
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Definition
| the formation of blood cells, begins in the 3rd week and continues throughout life. blood cells first develop from endothelial cells in blood islands of the yolk sack |
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Term
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Definition
| yolk sac, liver, thymus and spleen, bone marrow |
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Term
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Definition
| formed from different progenitor cells than in the adult |
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Term
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Definition
| hemoglobin weird letter 2, epsilon 2 |
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Term
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Definition
| hemoglobin alpha 2 gamma 2 |
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Term
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Definition
| hemoglobin alpha 2 beta 2 |
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Term
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Definition
| at the beginning of the 4th week, the lateral mesoderm separates into parietal and visceral mesoderm layers forming the intraembryonic colelom between these two layers |
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Term
| intraembryonic coelomic space |
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Definition
| formed between the parietal and visceral mesoderm. forms a U shape around the sides and head of the embryo disk. open and continuous with the extraembryonic coelom. |
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Term
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Definition
| as the embryo folds laterally, the edges of the embryonic disk composed to parietal (somatic) mesoderm and ectoderm are brought together to form this |
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Term
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Definition
| the intraembryonic coelom is now isolated from the extra embryonic coelomic space by the growing body wall. fusion of hte body all at the ventral midline encloses this space within the embryo. |
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Term
| parietal (somatic) mesoderm |
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Definition
| forms the body wall and the thin membranous lining of the future body cavity called the serosa |
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Term
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Definition
| covers the foregut and hindgut tubes as they form |
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Term
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Definition
| open into the yolk sac. with time the yolk sac decreases in size and is incorporated into this. it is now suspended in the coelomic cavity covered entirely by visceral mesoderm. |
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Term
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Definition
| visceral mesoderm forms it. it covers the viscera, the mesenteries, and the muscles and connective tissue of the gut. |
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Term
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Definition
| embryo folding in the cranial region causes the base of the original U shaped intraembryonic coelom to fold under the two arms of hte U, forming this. |
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Term
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Definition
| the proximal portion of the arms, now directed dorsocaudally, will become this. |
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Term
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Definition
| the distal portions of the arms are brought together on the ventral side of the embryo as the body wall folds forming this. |
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Term
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Definition
| when the intraembryonic coelom is no longer open to the extraembryonic coelom |
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Term
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Definition
| a ridge of tissue that forms on the lateral wall of each peritoneal cavity between the heart and developing lungs. they grow medially to separate the two pleural cavities from the pericardial cavity. |
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Term
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Definition
| the pleuropericardial folds form this. it is the outer layer of the pericardial cavity surrounding the heart. |
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Term
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Definition
| by the 7th week,the pleuropericardial folds fuse in the midline with undifferentiated mesoderm around the esophagus in this |
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Term
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Definition
| a mesoderm plate lying cranial to the cardiogenic region before embryo folding, and located just caudal to the heart after folding. it grows from the ventral body wall dorsally forming the central tendon of the diaphragm as it separates the pericardial and peritoneal cavities. |
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Term
| second division of the coelomic space |
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Definition
| created from the pleuroperitoneal fold and the septum transversume |
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Term
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Definition
| the pleuroperitoneal membranes join with the septum transversume to form this structure which separates the pleural and peritoneal cavities |
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Term
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Definition
| myoblasts grow into the dorsal mesentery to make muscle ingrowths from the body wall which contribute to the periphery of the diaphragm |
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Term
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Definition
| myoblasts and associated nerve fibers (3-5th spinal nerves) from the 3-5th cervical somites invade the septum forming this. |
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Term
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Definition
| as the embryo grows, the diaphragm assumes a thoracic position but still is innervated by these. the periphery of the diaphragm is innervated by thoracic nerves which serve the muscle fibers originating from the body wall after the diaphragm relocates in the thoracic region. |
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Term
| congenital diaphragmatic hernia |
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Definition
| occurs when one of the pleuroperitoneal folds fails to form or fuse with the other components of the diaphragm. occurs predominatly on the left side. the intestines, stomach, and even liver may be found in the thoracic cavity, limiting fetal lung development. infants often present with respiratory distress due to the comprimised lung |
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Term
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Definition
| a defect in closure of the thoracic cavity. the heart is located outside the body wall. |
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Term
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Definition
| a defect in the abdominal cavity closure where loops of intestine and sometimes other organs are located outside the body free in the amniotic cavity. the gut is usually to the right of the umbilicus. it is increasing in prevalence in younger mothers. the intestinal loops are not covered by the amnion, they are free in the amniotic cavity |
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Term
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Definition
| in normal development, intestinal growth outpaces growth of the abdominal cavity and the displaced intestinal loops are held for a number of weeks within the umbilical cord. as the abdominal cavity explands, the intestines return to the abdominal cavity. this defect results if the intestines fail to move back out of hte umbilical cord. the intestines are both covered by amnion and are within the umbilical cord. |
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Definition
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Definition
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Definition
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Definition
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Term
| Embryonic (or Fertilization) Age |
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Definition
| time measured from fertilization and is counted in weeks or days |
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Term
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Definition
| estimates embryonic age based on the woman's last menstrual period. counting begins before fertilization |
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Term
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Definition
| uses standardized morphological features that can be observed and used to accurately stage and compare developmental progression. based on clearly observable or measurable physical features |
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Term
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Definition
| embryo folds. body cavities and GI system forms. cranial and caudal neuropores close, the brain begins to develop and enlarge. pharyngeal arches form. heart is prominent over the ventral aspect of the embryo and pumps blood. limb bunds form, upper before lower. otic pits which will become the ears form. lens placodes form marking the future eye. |
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Term
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Definition
| paired structures in the head/neck region that are similar to somites in function. they are composed mainly of neural crest and will form much of the face and neck. |
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Term
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Definition
| head enlarges due to rapid development. face develops from facial prominences. nasoplacodes form and develope into a nasal pit. first pharyngeal arch has divided into the maxillary and mandibular prominences. germ cells migrate to the future gonad. kidney begins to form. lungs begin to develop as outgrowths from the foregut |
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Term
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Definition
| head continues to enlarge rapidly and is larger than the trunk. upper lip and nose form. upper limbs begin to regionalize and develop handplates with digital rays. lower limbs develop footplates. the developing intestines loop into the extraembryonic coelom within the umbillical cord until the 10tg week |
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Term
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Definition
| ossification begins in the long bones of the limbs. trunk and neck straighten. eyelids begin to form. abdomen enlarges due to growth of liver. abdominal surface now blends in with the cardiac prominence giving the body wall a more continuous silhouette. the yolk sac regresses to a small omphaloenteric duct |
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Term
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Definition
| fingers and toes are visible. caudal eminence is a tail like structure diseappears by the 8th week. the head is still disproportionally large but the trunk and limbs undergo rapid growth in this period. neck is established. eyelids fuse. ears develop. external genitalia are present but not differentiated sufficiently to determine gender. kidney begins to function late in this week. |
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