PS263 Chapter Notes - Chapter 10: Prenatal Development, Vas Deferens, Vasopressin
Document Summary
Sexual reproduction increases variation and thereby enables quick evolutionary adaptions to changes in the environment. Sex corrects errors: disadvantageous mutation in one gene could be balanced out by partner"s genes. Male and female mammals start with same anatomy during early stage of prenatal development. Both have a set of mullerian ducts (precursors to female internal structures) and wolffian ducts (precursors to male internal structures) Both have undifferentiated gonads on their way to becoming either testes or ovaries. The sry (sex determining region on y chromosome) gene causes primitive gonads to develop into testes which produce androgens that increase their growth and positive feedback. Androgens cause primitive wolffian ducts to develop into seminal vesicles and vas deferens. Testes produce mullerian inhibiting hormone mih which causes mullerian ducts to degenerate. Final result is development of a penis and scrotum. Because females don"t have sry gene, gonads develop into ovaries and wolffian ducts degenerate.
