Term
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Definition
| defines the large amount of yolk in eggs. (amphibians) |
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Definition
| mark used to give orientation while using the cross sectioning technique |
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Definition
| dark region in spermatids that will become mitochondria |
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Definition
| term defines the process of separating chromosomes |
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Term
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Definition
| DNA replication without a subsequent mitiotic event |
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Term
| In what direction do grasshopper testis develop |
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Definition
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Term
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Definition
| in grass hopper testis, found at the apical lobe. small primordial germ cells that undergo mitosis. |
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Term
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Definition
| the term applies to all cells after the first and before the second maturation division. |
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Term
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Definition
| these are round cells or tear drop shaped with haploid eccentric nuclei, which result from the second maturation division. |
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Term
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Definition
| the now haploid spermatids undergoes differentiation to become a mature sperm. the ealiest stage in spermiogenesis is seen as a typical resting cell nucleus with chromatin threads. In the next stage the cytoplasm becomes elongated to form a spindle-shaped head. Finally, the chromatin material will be condensed so that the nucleus will take a uniformly dark stain. |
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Term
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Definition
| mature sperm- these mature gametes or germ cells have long, thin and heavily stained heads and grayish filamentous tails which may be seven to eight times as long as the heads. The chromosomes cannot be identified in the nucleus by and staining procedure. |
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Term
| Direction of mammalian development |
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Definition
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Term
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Definition
| found in mammalian testis |
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Term
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Definition
| this stage is one of growth and nuclear preparation for the meiotic divisons that follow. The primary spermatocytes are located just inside the spermatogonia at the periphery of the tubule toward the lumen. When fully grown, the primary spermatocyte undergoes the first meiotic (reductional) divison resulting in the formation of two smaller daughter cells called secondary spermatocytes. |
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Term
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Definition
| during their transfomration, the spermatids are embedded in the cytoplasm of nurse cells. They are columnar cells attached proximally to the basement membrane and reaching distally to the lumen of the tubule. They lie at intervals in the wall of the seminiferous tubule. Hence, the mature spermatozoa may be found with its head embedded in the sertoli cells and the tail growing out toward the lumen of the tubule. These cells may be recognized by their nuclei, which contains a large, darkly stained nucleolus, and by their clear cytoplasm. some of the funtion ascribed to them in spermatogeneis and spermiogenesis are physical support, mediating movement of steroids, metabolites, etc., restring movement of macromolecules, and phagocytosing degenerating spermatogenic cells. |
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Term
| Intersitial cell of Leydig |
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Definition
| these cells are located between the seminiferous tubules and produce testosterone. |
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Term
| What simple layer surrounds the ovary |
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Definition
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Term
| what composes the bulk of the ovary |
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Definition
| stroma that is largely connective and intersitial tissues with blood vessels. |
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Term
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Definition
| small primary oocytes occur in clusters located just inside the germinal epithelium and lack surrounding granulosa cells. These clusters are known as egg nests. |
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Term
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Definition
| the primary oocyte becomes surrounded with a single layer of grnaulosa cells that serve to protect and mediate the transfer of nutrients to the ovum. The entire structure is termed the BLANK. It will be noted that the primary oocyte here is larger than an SPO in the egg nest. |
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Term
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Definition
| the granulosa cells of the primary follicle proliferate rapidly and the ovum, somewhat enlarged, becomes surrounded by several layers of these cells (the stratum granulosa) |
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Term
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Definition
| outised the granulosa cells an organized investment of connective tissue begins to form. The theca will ultimately differentiate into the theca interna and the theca externa. |
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Term
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Definition
| proliferation within the layer of granuloca cells proceeds rapidly and irregular fluid filled spaces appear among the cells. these spaces rapidly unite to form a cavity. This cavity is BLANK |
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Term
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Definition
| The mature graffian follicle projects from the surface of the ovary. The antrum is filled with a fluid known as liquor folliculi. Such a follicle is nearly ready to rupture and release the contained egg cell. in the course of the development it has axquired a degree of differentiation. The egg cell at this stage is commonly called an ovum, but in homology with the male gametes it is properly termed a primary oocyte. It has grown to a size many times that of the follicle cells that surround it, and its cytoplasm is dotted with granules of stored food material (yolk). |
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Term
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Definition
| The abundant store of yolk in avian oocytes that causes the nucleus to be displaced peripherally. |
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Term
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Definition
| consists of mucopolysaccharide and trypsin digestible material. it is a non cellular secreted layer that surround the primary oocyte. |
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Term
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Definition
| "yellow body" produces progesterone. |
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Term
| When does extrusion of the first polar body occur in mammals |
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Definition
| before or concurrent with ovulation |
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Term
| When does extrusion of the second polar body occur |
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Definition
| after penetration fo the cell membrane by one or more sperm. |
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Term
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Definition
| "white body" the lysed corpus luteum |
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Definition
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Definition
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Term
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Definition
| found in insect larval cells. They are chromosomes that undergo DNA replication without a subsequent mitotic event(endomitosis). They have alternating light and dark bands. |
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Term
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Definition
| the dark bands in polytene chromosomes. not transcribing. |
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Term
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Definition
| The light bands in polytene chromosomes that are transcribing |
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Term
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Definition
| Period of prepartion for division; produciton of nucleotides, amino acids, enzyme systems, and reserve energies occurs; a very long phase and cell is metabolically active. Also referred to as the gap I phase. |
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Term
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Definition
| Molecules necessary for mitotic development produced (spindle fiber proteins, primarily microtubules); a fairly short phase |
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Term
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Definition
| mitotic spearation of the chromosomes(karyokinesis) followed by cell division or cytokinesis |
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Term
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Definition
| the actual separation of the chromosomes, the first stage of mitosis or meiosis |
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Term
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Definition
| the separation of the cell cytoplasm; resulting cells may be equal or unequal in size. |
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Term
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Definition
| chromosomes condense, nucleolus disappears, centrioles replicate, nuclear envelope breakdown. |
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Term
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Definition
| Mitotic spindle organizes and directs chromosmes to equatorial plate. |
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Term
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Definition
| chromatids separate, and are pulled to opposite ends of the cell. |
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Term
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Definition
| nuclear envelope reforms and chromosomes uncoil and become indistint, nucleoli reappear and cytoplasm divides. |
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Term
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Definition
| chromosomes have replicated forming sister chromatids which are closely associated thus appearing as thin threads. threads are long, thin and lightly stained. homologous pairs have not come together thus individual strands are not distinquishable. Cell is enlarge. the sex chromosome X is condensed and seen as a dark oval on one side of the chromosomal mass. |
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Term
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Definition
| (synaptene) begins as sister chromatids start forming synapses with their homologous pair. The homolous pair of sister chromatids is termed a tetrad. The yoked threads chromatin appears broken into individual threads. X chromosome is still visible. the chromosomes seem to converge toward the side of the nucleus nearest the centrosome. |
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Term
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Definition
| starts at the conclusion of synapses formation. close association of homologous paiirs gives the illusion that the cell has less DNA than previous stages. chromosomes appear as thick threads.Crossing over occurs at this stage or, more frequently in the following stage. |
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Term
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Definition
| homologous pairs start to separate but remain attached at regions where crossing over occurred. homologous pairs have forked ends. Eggs of many species arrest at this stage for several months or years. RNA synthesis is occuring and lampbrush chromosomes in some species are seen |
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Term
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Definition
| Region where crossing over occured |
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Term
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Definition
| When eggs stop in the diplotene phase |
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Term
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Definition
| hindbrain"moving apart" condensation and repulsion continue. chromosomes detach from nuclear envelope and RNA synthesis has stopped. Terminalization of chiasmata on the bivalent pairs continues so that chromosomes show curious shapes such as rings, crosses, bars, coils. the nucleus is now prepared for the two critical maturation divisions. |
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Term
| What type of reproductive system to earthworms have |
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Definition
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Term
| what type of reproductive system do zebra mussels have |
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Definition
| diecious meaning they have separate sexes |
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Term
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Definition
| a nematode parasite found in the intestines of some mammals. |
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Term
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Definition
| a group of four chromosomes |
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Term
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Definition
| the process where a cavity is formed after several cleavages. |
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Term
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Definition
| process where the archenteron is formed. also called gastrulation |
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Term
| How do you identify an unfertilized egg |
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Definition
| enlarged nucleus and the germinal vesicle. |
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Term
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Definition
| contains more yolk, lighter |
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Term
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Definition
| slightly darker and posses a greater concentration of organelles. |
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Term
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Definition
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Term
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Definition
| the extra cellular coat of the egg |
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Term
| when does fertilization of the egg occur |
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Definition
| when in 2nd metaphase arrest |
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Term
| where does sperm generally bind |
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Definition
| 30 degrees above the equator in the animal hemisphere |
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Term
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Definition
| the exposed cytoplasm that is seen right after the sperm binds. It is slightly lighter than its neighboring coritcal cytoplasm |
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Term
| how does cleavage in amphibians take place |
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Definition
| bilateral and holoblastic. Due to the uneven distribution of yolk, cleavage through the vegetal hemisphere occurs slightly slower than through the animal hemisphere. the first cleabage is meridional and bisects the grey crescent. the vitelline envelope has elevated from the oolemma to form the fertilization envelope. |
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Term
| how does the second cleavage in amphibians take place |
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Definition
| meridonal and perpendicular to the first cleavage plane. |
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Term
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Definition
| name of organisms at the 32 cell stage |
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Term
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Definition
| the fluid filled cavity that forms around the 256 cell stage. it becomes lined with epithelial cells.it forms between the animal and vegetal hemispheres. the roof is arched and fromed from micromeres while the floor is formed from macromeres. |
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Term
| where does gastrulation begin. |
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Definition
| at the dorsal edge of the grey crescent as cells turn inward into the blastocoel via involution. the site of involution is the dorsal blastoporal lip. |
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Term
| what is the predominant process occurring in the 18 hr chick embryo |
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Definition
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Term
| whats does the embryo consist of prior to grasturlation |
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Definition
| a small blastodisc of dividing cells resting on a large quantity of yolk. |
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Term
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Definition
| consists of the epiblast layer of cells(which ultimately gives rise to the chick embryo), the hyposblast (which contributes to extraembryonic membranes), the blastocoel cavity between the epiblast and hypoblast, and the subgerminal cavity located between the hypoblast and the underlying yolk mass. |
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Term
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Definition
| forms at the posterior end of the blastodisc as lateral mesodermal cells migrate toward the midline of the epiblast and into the blastocoel. Once the mesodermal cells reach the midline they migrate anterior. narrowing and thickening along the midline of the epiblast and into the blastocoel. once the mesodermal cells reach the midline they migrate anterior, narrowing tand thickening along the way creating the primitive streak. As the primitive streak narrows a depression develops in the strea, which is the point of passage of the cells into the blastocoel.these primitive ridges are analogous to the ventral lip of the blastopore. at the anterior most migration of the primitive streak, the anterior end of the streak develops into the primitive know( henson's node or pirmitive pit), a thickening of epiblast cells and is the equibalent of the amphibian dorsal lip of the blastopore. cells migrate through this pit, into the blastocoel, and turn anterior to develop into the notochord, head mesenchyme, and foregut. cells also migrate laterally over the primitve ridges into the blastocoes forming the endodermal and mesodermal structures. |
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Term
| in what direction does development occur in the chick |
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Definition
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Term
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Definition
| (henson's node) anterior end of primative streak, equivalent to dorsal lip. |
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Term
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Definition
| depression in the center of the knot (analogous to the dorsal blastoporal lip) |
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Term
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Definition
| depression in primitive streak whre cells migrate laterally into the blastocoel( analogous to ventral lips of the blastopore) |
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Term
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Definition
| thickened edges of primitive streak |
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Term
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Definition
| cranial most region of embryo undergoes downward folding separating the future head region from yolk |
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Term
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Definition
| central, clear region of blastodisc where epiblast is elevated above underlying yolk |
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Term
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Definition
| margin of blastodisc where epiblast is closely associated with underlying yolk |
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Term
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Definition
| ectodermal lined cavity. happens as the head fold continues to enlarge. it separates the anterior most region of the embryo from the underlying yold. |
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Term
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Definition
| lined with the endoderm. Also formed as the head fold continues to enlarge. it is continuous with the yolk. the cranial intestinal portal marks the anterior edge of the opening connecting the yolk sac with the foregut. |
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Term
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Definition
| anteror to the head fold, clear region devoid of mesoderm |
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Term
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Definition
| process where the ectodermal cells on the dorsal surface of the embryo thicken to from the neural plate |
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Term
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Definition
| the precursor to the brain and spinal cord |
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Term
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Definition
| a small pore created where the anterior end of the neural tube does not completely close. |
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Term
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Definition
| mesoderm cells collect lateral to the neural tube to from this thick band. a sportion divides into blocks of tissue called somites. |
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Term
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Definition
| precursors to red blood cells and vitelline blood vessels. develope in the area opaca. |
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Term
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Definition
| solid cylinderical rod running length of embryo just ventral to neural tube |
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Term
| what 3 generalized regions does the neural tube develop into in the 33 hour chick |
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Definition
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Term
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Definition
| when the anterior region rotates laterally so the head region now rests on its left side. |
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Term
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Definition
| ventral bending, sharp bend in floor of mesencephalon |
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Term
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Definition
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Term
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Definition
| ventral opening in the optic cup, site where optic nerve will enter eye |
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Term
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Definition
| sphere in center of optic cup, will develop into lens |
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Term
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Definition
| upper half of 1st brachial arch, will develop into upper jaw |
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Term
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Definition
| lower half of 1st branchial arch, will develop into lower jaw |
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