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During what weeks is development in the embryo stage? |
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What is it called when cells arrange into three germ layers? |
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gastrulation, ectoderm, endoderm, and mesoderm. |
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What do primordial germ cells do? |
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Migrate to developing gonads and turn into spermatogonia or oogonia. |
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GPCS are diploid what happens after meiosis |
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gpcs form gazettes which are haploid |
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Gazettes that undergo cytoplasmic diffentiation are called? |
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Where does fertilization take place? |
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What is the product of fertilization? |
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After a increase in the number of cells what is formed? |
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blastomere. No size increase in embryo |
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Morula undergoes reorganization that results in? |
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Inner cell mass (embryoblast) and outer cell mass (trophoblast) |
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How do you get dizygotic twins? |
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Fertilization of 2 ovulate eggs. 2/3. |
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How do you get monozygotic twins |
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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? |
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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 |
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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 |
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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 |
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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 |
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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? |
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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 |
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What does the first wave of migrating form? |
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The outer layer of cells form what |
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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? |
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What does syncytiotrophoblast produce |
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Human chronic gonadotropin hCG |
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As the primary yolk sac forms why appears? |
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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 |
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Blood vessels that establish the uteroplacental circulation (tertiary choronic vili) |
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When does gastrulation start? |
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What are the three parts of the primate streak? |
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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? |
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What do epiblast cells do when they travel into the primitive streak? |
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Epithelial to mesenchymal transformation |
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When the hypoblast is displaced during EMT what is formed |
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epiblast cells continue to migrate between the endoderm and ectoderm and form what? |
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What do the 5th population of mesodermal cells that migrate Cranially from the primitive node form? |
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What happens if the primitive streak doesn't become insignificant |
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sacrococcygeal teratoma, benign tumor that can be removed |
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What does the ventral layer of the notochord fuse wit? |
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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? |
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Chordoma can develop anywhere along the notochord and can infiltrate bone and muscle. |
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paraxial mesoderm formed what? |
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te splanchnic mesoderm forms? |
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give coverings of viscera and part of the visceral wall |
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Somatic mesoderm does what? |
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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 |
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The two expression in the ectoderm form? |
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oropharyngeal membrane (breaks down in 4th week. cloacal membrane (7th week). |
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Neural plate forms from the |
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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? |
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