the notion of gender and many of the factors that contribute to the spectrum. Gender includes, but is not limited by behaviour or gonadal sex. With this in mind, please discuss gender across the vertebrates in terms of chromosomes, gene expression, receptors, hormones, gonads, gametes, genitalia, and environmental factors (internal, external, and uterine).
Sex determination of vertebrates has long been done based on gonadal differentiation into either ovaries or testes. In general there are two mechanism for sex determination, genetic sex determination or GSD and external sex determination or ESD. In vertebrates ESD is reduced to only temperature sex determination (TSD). Primary mechanism of sex determination is not understood properly and occurs by differentiating Y chromosome. Development of gonads in vertebrates have bipotential genital ridges the cortex and medulla. So sex differentiation happens based on development of these two. Ovaries develop from growing cortex and testes develop from medulla and these two process the antagonist to each other.
Vertebrate genes involved in sex determination are mostly conserved but gene expression varies among species. Aromatase (CYP19) regulates gonadal estrogen level is thought to the main target of thermo sensitive factor for TSD. Estrogen level also influence sex determination. Yolk steroids and embryonic steroid are the source of hormones that play role in TSD. amh-sox9 affects the appearance of testes in case of TSDs.
Telecost fishes are the largest group of vertebrates and exhibits a variety of sexuality. It is categorized into gonochorism, sequentia hermaphrodite or unisexual reproduction. Four sex determining gene in vertebrates are sry, dmrt1, dmy and DM-W.
the notion of gender and many of the factors that contribute to the spectrum. Gender includes,...