Flashcards in Sex Determination and Gonadogenesis Deck (17):
A region with sufficient homology to allow crossovers between X and Y chromosomes
Testis determining factor: a region that can be carried along with the pseudoautosomal region in rare cases
TDF is sufficient to confer maleness.
Two results of TDF crossover
Either XX , but with testes; or XY, but not external male features
Sry expression is sufficient to confer maleness
What is Sry?
a transcription factor
Relationship between TDF, Sry, Sox9, Eif2s3x
TDF is a region that builds Sry, a transcription factor, and Eif2s3y, a translation initiation factor. Sry leads to Sox 9 expression from the autosome.
Indistinguishable stage of embryo development between males and females
Three important components during the indifferent stage
Sex Cords, Wolffian duct and Mullerian duct
Male Duct Differentiation
Wolffian duct : vas deferens; Sex cords: seminiferous tubules; Mullerian duct: eventually degenerates
Female Duct Differentiation
Wolffian duct degenerates;Surface epithelium-->surface of ovary, Mullerian duct: oviduct/fallopian tube
What becomes the urinary and reproductive tract?
Male Gonadal Differentiation [factor,3 components,4 chemicals, degeneration]
Sry leads to Sox9 expression, formation of testes, leydig cells, and sertoli cells. Lydia cells create testosterone which is converted by 5alpha reductase to Dihydrotestosterone. Sertoli cells secrete anti mullerian duct hormone
Female Gonadal Differentiation [factor,3 components,4 chemicals, degeneration]
Wnt4 expression creates Ovary, Thecal cells, and Granulosa cells. Theca cells create testosterone, and Granulosa cells produce aromatase, which converts Testosterone to Estrogen.
What are testosterone and DHT used for?
Secondary male characteristics.
Androgen Insensitivity Syndrome [testosterone & dihydrotestosterone] mutation in the androgen receptors. Female outer phenotype, but with male internal organs.