Trans Twitter Topics

@TransEthics Normally the Y chromosome carries 27 genes, only 4 are related to sex. One, the SRY, determines (via the SOX9 gene) whether testes or ovaries form in the early fetus. Another 3 determine sperm production if testes form.

@TransEthics The SRY is just a signaler to 3 dark DNA areas to produce more SOX9 genes, above a certain threshold testes form, below that ovaries.

But that is just the start of the story. If ovaries form then another gene, FOXL2, keeps them as ovaries.

@TransEthics FOXL2 works with estrogen receptors to keep the ovary as an ovary without which it would turn into testes and start producing testosterone by inhibiting SOX9 production.

@TransEthics FOXL2 works with estrogen receptors to keep the ovary as an ovary without which it would turn into testes and start producing testosterone by inhibiting SOX9 production.

@TransEthics Male and female mammals produce SOX9 as far as I know all their lives (I need to check up on that) and even if there are already ovaries if the level becomes high enough then the ovaries will turn into testes.

@TransEthics But FOXL2 production depends on enough estrogen and/or the estrogen receptors working correctly. If something goes wrong with either then SOX9 production increases and existing ovaries will turn into testes and produce testosterone.

@TransEthics So there is a feedback loop: No SRY means less SOX9, thus ovaries form. They produce estrogen which causes FOXL2 production which suppresses SOX9 production to keep the ovaries as ovaries. Is something goes wrong and SOX9 levels climb enough then those ovaries will become testes