ACB 406.3 Lecture Notes - Lecture 20: Sox9, Amphiprioninae, Organ Culture

• School: U of S
• Department: Anatomy and Cell Biology
• Course: ACB 406.3
• Professor: Helen Nichol

Document Summary

In mammals, males are xy (heterogametic) and females are xx. In birds, females are heterogametic (zw) and males are zz. Crocodiles, turtles and some other lower vertebrates have no sex differences in chromosomes sex is determined by temperature: for some animals, lower temperature produces males while higher temperatures produce females. In crocodiles, high and low temperatures produce females while intermediate temperature produces males. Many vertebrates mate or produce gametes seasonally (humans are unusual) Ascidians (sea potato) are hermaphroditic: there is an ovotestis but gametes are produced at different times to avoid self- fertilization. Development of gonads is initially directed by the incubation temperature of the egg during the middle third of embryonic development. In organ culture systems it has been shown that the expression sox9 and 3 other genes are regulated by temperature: low temperature, sox9 is expressed produce males, high temperature, no sox9 expression produce females. Both male and female gonads arise from genital ridges.