(05-16-2022 07:03 AM)shere khan Wrote: XX
Apparently there are very rare exceptions-has to do with the SRY gene. And a few other syndromes.
https://en.wikipedia.org/wiki/Sex_chromosome
"...However, a small percentage of humans have a divergent sexual development, known as intersex. This can result from allosomes that are neither XX nor XY. It can also occur when two fertilized embryo fuse, producing a chimera that might contain two different sets of DNA one XX and the other XY. It could also result from exposure, often in utero, to chemicals that disrupt the normal conversion of the allosomes into sex hormones and further into the development of either ambiguous outer genitalia or internal organs.[7]
There is a gene in the Y chromosome that has regulatory sequences that control genes that code for maleness, called the SRY gene.[8] This gene produces a testis-determining factor ("TDF"), which initiates testis development in humans and other mammals. The SRY sequence's prominence in sex determination was discovered when the genetics of sex-reversed XX men (i.e. humans who possess biological male-traits but actually have XX allosomes) were studied. After examination, it was discovered that the difference between a typical XX individual (traditional female) and a sex-reversed XX man was that the typical individuals lacked the SRY gene. It is theorized that in sex-reversed XX men, the SRY mistakenly gets translocated to an X chromosome in the XX pair during meiosis.[9]..."
https://en.wikipedia.org/wiki/Sexual_dif..._in_humans
And this:
"...The following are some of the variations associated with atypical determination and differentiation process:[19]
A zygote with only X chromosome (XO) results in Turner syndrome and will develop with female characteristics.[5]
Congenital adrenal hyperplasia - Inability of adrenal to produce sufficient cortisol, leading to increased production of testosterone resulting in severe masculinization of 46 XX females. The condition also occurs in XY males, as they suffer from the effects of low cortisol and salt-wasting, not virilization.
Persistent müllerian duct syndrome - A rare type of pseudohermaphroditism that occurs in 46 XY males, caused by either a mutation in the Müllerian inhibiting substance (MIS) gene, on 19p13, or its type II receptor, 12q13. Results in a retention of Müllerian ducts (persistence of rudimentary uterus and fallopian tubes in otherwise normally virilized males), unilateral or bilateral undescended testes and sometimes causes infertility.
XY differences of sex development - Atypical androgen production or inadequate androgen response, which can cause incomplete masculinization in XY males. Varies from mild failure of masculinization with undescended testes to complete sex reversal and female phenotype (Androgen insensitivity syndrome)
Swyer syndrome. A form of complete gonadal dysgenesis, mostly due to mutations in the first step of sex determination; the SRY genes.
A 5-alpha-reductase deficiency results in atypical development characterized by female phenotype or undervirilized male phenotype with development of the epididymis, vas deferens, seminal vesicle, and ejaculatory duct, but also a pseudovagina. This is because testosterone is converted to the more potent DHT by 5-alpha reductase. DHT is necessary to exert androgenic effects farther from the site of testosterone production, where the concentrations of testosterone are too low to have any potency...."
