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        | During what weeks is development in the embryo stage? |  | Definition 
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        | What is it called when cells arrange into three germ layers? |  | Definition 
 
        | gastrulation, ectoderm, endoderm, and mesoderm. |  | 
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        | What do primordial germ cells do? |  | Definition 
 
        | Migrate to developing gonads and turn into spermatogonia or oogonia. |  | 
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        | GPCS are diploid what happens after meiosis |  | Definition 
 
        | gpcs form gazettes which are haploid |  | 
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        | Gazettes that undergo cytoplasmic diffentiation are called? |  | Definition 
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        | Where does fertilization take place? |  | Definition 
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        | What is the product of fertilization? |  | Definition 
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        | After a increase in the number of cells what is formed? |  | Definition 
 
        | blastomere. No size increase in embryo |  | 
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        | Morula undergoes reorganization that results in? |  | Definition 
 
        | Inner cell mass (embryoblast) and outer cell mass (trophoblast) |  | 
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        | How do you get dizygotic twins? |  | Definition 
 
        | Fertilization of 2 ovulate eggs. 2/3. |  | 
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        | How do you get monozygotic twins |  | Definition 
 
        | An embryo splits 1/3. When the inner cell mass does not completely separate the two embryos occupy a single amnion and are conjoined. |  | 
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        | When does the Modula reach the uterus? |  | Definition 
 
        | Between 3 and 4 days of development. In 5 days it hatches from zonal pellucid and interacts with endometrium |  | 
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        | At approximately day 6 the blastocyst attaches to the endometrium and differentiates between 2 layers |  | Definition 
 
        | cytotrophoblast inner layer. And the syncytiotrophoblast outer layer which extends and invades the endometrial connective tissue |  | 
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        | What major event has happened by the end of one week |  | Definition 
 
        | the blastocyst is implanted in the compact layer of the endometrium and is deriving nourishment from eroded maternal tissue |  | 
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        | What is an ectopic pregnancy |  | Definition 
 
        | If the blastocyst implants in the peritoneal cavity on the surface of the ovary epithelium responds with increased vascularity. Life threatning |  | 
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        | What do the layers reform into |  | Definition 
 
        | epiblat I the upper layer of columnar cells. And the hypoblast is te internal lowerlayer of cuboidal cells |  | 
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        | Where does fluid collect? |  | Definition 
 
        | In between the epiblast and the overlying trophoblast. The epiblast develops into a thin membrane. (amnion) |  | 
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        | By what week does the amnion enclose the entire embryo |  | Definition 
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        | What does the first wave of migrating form? |  | Definition 
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        | The outer layer of cells form what |  | Definition 
 
        | extraembryonic mesoderm which forms the Chorioni c cavity which separates the embryo from the outer wall chorion |  | 
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        | The primary yolk sac is displaced which ;is replayed by the secondary yolk sac |  | 
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        | By day 13 what suspends the yolk sac? |  | Definition 
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        | What does syncytiotrophoblast produce |  | Definition 
 
        | Human chronic gonadotropin hCG |  | 
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        | As the primary yolk sac forms why appears? |  | Definition 
 
        | Lacunae appear and will eventually fill with blood and other fluid from mother |  | 
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        | extraembyrionic mesoderm associated with cytotrophoblast that penetrates primary villi |  | 
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        | By the end of the 3rd week what has developed |  | Definition 
 
        | Blood vessels that establish the uteroplacental circulation (tertiary choronic vili) |  | 
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        | When does gastrulation start? |  | Definition 
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        | What are the three parts of the primate streak? |  | Definition 
 
        | The primitive groove (in the middle) the primitive node (cranial end) and the primitive pit (dispersion continuous w/ groove |  | 
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        | What is called when epiblast comes into touch with primitive streak? |  | Definition 
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        | What do epiblast cells do when they travel into the primitive streak? |  | Definition 
 
        | Epithelial to mesenchymal transformation |  | 
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        | When the hypoblast is displaced during EMT what is formed |  | Definition 
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        | epiblast cells continue to migrate between the endoderm and ectoderm and form what? |  | Definition 
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        | What do the 5th population of mesodermal cells that migrate Cranially from the primitive node form? |  | Definition 
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        | What happens if the primitive streak doesn't become insignificant |  | Definition 
 
        | sacrococcygeal teratoma, benign tumor that can be removed |  | 
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        | What does the ventral layer of the notochord fuse wit? |  | Definition 
 
        | Endoderm. Will form the notochordal plate and detached from the endoderm. Free eds fuse as it rolls up ion the space between Endo and ecto |  | 
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        | What happens when the notochord doesn't disappear fully? |  | Definition 
 
        | Chordoma can develop anywhere along the notochord and can infiltrate bone and muscle. |  | 
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        | paraxial mesoderm formed what? |  | Definition 
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        | te splanchnic mesoderm forms? |  | Definition 
 
        | give coverings of viscera and part of the visceral wall |  | 
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        | Somatic mesoderm does what? |  | Definition 
 
        | Dorsal layer gives rise to inner lining of body wall and parts of limbs |  | 
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        | The remaining epiblast cells that cannot mirage from the |  | Definition 
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        | The two expression in the ectoderm form? |  | Definition 
 
        | oropharyngeal membrane (breaks down in 4th week. cloacal membrane (7th week). |  | 
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        | Neural plate forms from the |  | Definition 
 
        | Ectoderm. It folds in on itself by the 3rd week making the neural tube hitch will be the CNS |  | 
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        | Neural crest cells migrate and give rise to? |  | Definition 
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