Reproductive Systems

Reproductive Systems - Reproductive Systems Sex...

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Reproductive Systems Sex Determination We are all the same through about 5-6 weeks of gestation Somewhere around 6-7 wks, the SRY gene (sex-determining region of the Y) is activated/not. SRY gene codes for a protein called Testis-Determining Factor (TDF) initiates development of male reproductive anatomy, particularly the testes. Testes stimulate mesonephric ducts to become male reproductive duct system secrete testosterone secrete mullerian-inhibiting factor (MIF) which causes degeneration of paramesonephric (mullerian) ducts. *Female development occurs when this system is not activated. External genitalia Everyone starts out the same Around 8-9 weeks, the testosterone generated by the newly-developed testes will steer external development toward male reproductive anatomy. Phallus penis, with glans Urogenital folds surrounds urethra inside penis Labioscrotal folds scrotum Lack of testosterone will result in female external anatomy Phallus clitoris Urogenital folds labia minora Labioscrotal folds labia majora Discontinuity of internal/external structures Androgen Insensitivity Syndrome (AIS) -Person genetically male (XY) -Develops testes during development -Body cells don’t respond to testosterone External anatomy defaults to female Interestingly, certain structural genes on the Y chromosome are still operational, and are expressed normally. Male Reproductive System Testes are divided into compartments, in which coiled up tubes (seminiferous tubules) reside. Seminiferous tubes are where spermatozoa are generated.
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All seminiferous tubes join at the rete testis. Spermatogenesis The outer surface of seminiferous tubules has spermatogonium. Spermatogonia give rise to the primary spermatocytes (through mitosis).
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This note was uploaded on 03/22/2009 for the course BIOL 252 taught by Professor Johnson during the Spring '07 term at UNC.

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Reproductive Systems - Reproductive Systems Sex...

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