BIOL 1F25 Lecture 19: Lecture 19
30 Jan 2013
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Document Summary
Sex determination and differentiation: embryologic origin of the reproductive system genital ridge. At 4th week, intermediate mesoderm gives rise to mesonephros; the mesonephric (wolffian) ducts give rise to epididymis and vas deferens in male. At 6th week, intermediate mesoderm give rise to paramesonephric (m llerian) ducts, which give rise to oviducts and uterus in female. Hox genes are involved in a/p patterning of urogenital tract. Arise in primitive streak and endoderm, migrate to yolk sac, then back to. In females, number of germ cells spikes the quickly falls in fetus, and experiences steady decline throughout life; in males, number of germ cells are constantly renewed. Can be used as a source of embryonic stem cells. Fate of pgc (male g1 arrest, female prophase i arrest) in embryo is determined by environment, but postnatal fate depends on genetic makeup. Testis development requires sry, a txn factor coded by the y. Other factors besides sry also determine sex.
