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when is genetic sex determined? conception which gamete determines sex? sperm since ova carry only X what is the default pathyway for sex determination? female pathway when does most of the sex determining development occur? in the first trimester what is the urogenital sinus? common primordium for the development of external genitalia what are the internal ducts of the male? and what were they originally both made from? epididymis and vas deferens the Wolffian duct what are the internal ducts of the female? and what were they originally both made from? the uterus and the fallopian tubes the Mullerian duct what determines a male in humans? presence of Y chromosome? What syndrome comes from XXY? Klinefelter what are the symptoms of Klinefelter syndrome? small penis, long legs, gynecomastia, scoliosis, obesity, hypovirilisation What syndrome comes from XO? Turner What are the symptoms of Turner syndrome? lymphoedema, prominent ears, loose folds of skin on the neck, shorter height, narrow deepset hyperconvex fingernails what is the difference in crossing over between X chromosomes and Y chromosomes? x chromosomes normally cross all down their length y chromosomes only have a small pairing region what is sry? sex determining region of Y where is sry found? on the non pairing region of the Y chromosome what does sry do? acts as a switch to promote primordial gonads change into testis what sort of problems can happen to the sry gene? deleted sry on a mutant Y chromosome --> XY female transfer onto the X chromosome-->XX male what other substance is important for male development? anti-mullerian hormone what promotes the maintenance of the Wolffian ducts? testosterone from the testes where is AMH secreted from? the testes what does AMH do? encourages regression of mullerian duct what happens if XY doesn't produce AMH? Persisitent Mullerian Duct Syndrome what happens chemically to testosterone? Testosterone-> 5αreductase-> 5α-dihydrotestosterone (DHT) what results in the development of male external genitalia? testosterone where is the origin of the testes? abdominal region, near the kidneys what is it called when the testes fail to descend? cryptorchidism what is the most common ailment of newborn males and what % of live births does it occur in? cryptorchidism 1-4% what type of babies is cryptorchidism more common in? premature babies low birth-weight babies what are the consequences in the adult of cryptorchidism? spermatogenesis is inhibited risk of testicular tumours what happens in males with androgen-insensitivity? testicular feminization- the testes complete the trans-abdominal migration but remain in the inguinal region what are the characteristics of androgen insensitivity? phenotypically female don't menstruate have blind ended vagina