BIOL30001 Lecture Notes - Lecture 21: Pseudoautosomal Region, Sertoli Cell, Seminiferous Tubule
16 Oct 2018
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Document Summary
Lecture 21 sex determination and sexual di erentiation. Sex determination refers to the moments embryo decides to go down male or female developmental pathway. Sexual di erentiation refers to everything after that point. In mammals, male and female embryos initially look alike. Identical indi erent gonads form on the embryonic kidney early in development and external genitalia is the same. Bipotential system = potential of urogenital and gonadal systems to go either of two developmental pathways. Note: female sex is the default, absence of male marker = female, presence of male marker = male. Determination of sex: mechanism that causes sex determination varies vastly across species, environmental e. g temperature selected development, genetic xx/xy mammals; zw/zz bird; some snakes, x : autosome ration in insects i. e. xx/xo. Genetic regulation of gonad di erentiation: in males: sry activates a whole genetic cascade that initiates sertoli cell fate testis, in females: a whole genetic cascade is activated only in the absence of.
