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17 Cards in this Set
- Front
- Back
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what is spermatogenesis ?
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production of 4 spermatids from the primordial germ cell.
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what is the trophoblast?
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outer layer of cells surrounding blastocoele (blastocyst cavity) and provides nutrients.
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what is the inner cell mass?
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forms embryo later on
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what condition is the uterus in when implantation takes place?
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the endometrium consists of the compact layer, spongy vascularised layer and a basal layer.
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what happens to the penetration gap in the endometrium after the embryo has embedded completely?
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closed up by migrating endothelial cells.
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when the synctiotrophoblast penetrates the endometrium gaps are made, what are these and what are they for?
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sinusoids, used after fusion with lucunae to let maternal blood enter
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what is the role of hCG?
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prevents the degeneration of the corpus luteum which is secreting progesterone, the hormone that keeps the uterine lining as it is to sustain pregnancy.
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when does gastrulation occur?
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week 3
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what is the primitive streak and where does it form?
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it is a grove that forms the major body axis starting on the surface of the epiblast.
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what happens to the epiblast cells when they invaginate and migrate?
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the lose their properties (polarity and basal lamina) and change their morphology into 'bottle' cells. They then resume to their mesenchymal shape when within the streak.
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how is the mesoderm formed?
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cells leave the primitive node and streak off at different crania-caudal levels.
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mesoderm divided into 3 levels which are..?
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paraxial (nearest notocord), intermediate and lateral plate. Cavities then form in the lateral plate separating 2 layers which are now the somatic mesoderm and splanchnic mesoderm.
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in which way to somites form?
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from cranial to caudal end.
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what happens to the mesonephros is the formation of kidneys from intermediate mesoderm?
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it degenerates into the metanephros which then goes on to form the kidneys.
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what happens to the paramesonephric and mesonephric ducts in gonad formation?
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in male para regresses and meso becomes vas deferrals. in female para becomes oviduct and from either side they fuse becoming the uterus and vagina. Meso regresses.
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what does the mesoderm essentially produce and from which segments to these parts originate?
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the paraxial mesoderm produces the vertebrae and the head and muscles, the somatic (lateral plate) produces the limbs and bones, and the intermediate produces the kidneys and gonads.
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what is and why is spina bifida caused?
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incomplete closure of the neural tube during development perhaps from a lack of folate in pregnancy.
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