Biology 3601A/B Lecture Notes - Lecture 16: Sequential Hermaphroditism, Aromatase, Crocodilia
21 Oct 2016
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Lecture 16 endocrinology 2: temperature-dependent sex determination. Sry sex-determining region on y chromosome. Once there are ovaries/testes, sexual differentiation depends on hormonal signals. Sex of the animal is determined by its chromosomes. This is the case for all mammals: xx and xy system. Small part of the embryo, the germinal ridge either develops into ovaries or testes. Expression of sry which leads to testes determination factor and testes development. Gnrh being secreted at a constant (tonic) level. In females, without sry we get ovary development they secrete gnrh cyclically, which is why we have monthly cycles. Z chromosome = (cid:494)primordial gonad(cid:495) secretes estrogens. (most birds only have a left ovary, but paired testes) Overrides any male signals (e. g. from implanted tissue) (takes estrogen treatment to get female behaviour, and treating females with aromatase inhibitors. Birds only have one ovary, the left ovary. Aromatase converts testosterone to estradiol if you block aromatase with an inhibitor you get a male.
