Genetic sex

Genetic sex determines the true, or gonadal, sex (from the Greek. Gone - the seed), that is, the floor due to the structure of the sex gland (testicle or ovary). Thus, the XY pattern, characteristic only for male cells and making them incompatible with the immunological system of the female body, programs, due to the presence of the SRY gene in the Y-chromosome, the transformation (from 4-8th week) of the embryonic gonads of the male fetus into testes capable of spawn sperm.
In chromosome X of pattern XX, there is a DSS gene that directs the development of an indifferent gonad into the ovaries that are capable of spawning eggs. The appearance of the testicles or ovaries causes a gamete floor (from the Greek. Gametes - spouse, gamete - spouse).
Thus, the DSS gene plays the same role in pattern XX as the SRY gene in the XY pattern. At the end of the 3rd month, the testes begin to produce the male sex hormone testosterone (androgens). There is a hormonal sex, which in the embryo determines the differentiation of the internal reproductive organs (internal morphological floor) and external genitalia (external morphological floor), as well as special nervous mechanisms, the so-called “sexual centers”, which further regulate the masculine or feminine behavior of a person. With the onset of puberty in boys, the number of androgens increases, as they are produced not only in the adrenal cortex, as in women, but also in the male sex glands. And the more androgens in the body, the more masculine behavior manifests itself.
The hypothalamus, in which the sexual centers are located, not only differentiates under the influence of germinal hormones, but is itself a psycho-endocrine organ; his prenatal program, which focuses on male and female behavior, determines the nature of his reaction to the sex hormones of puberty, and this reaction, in turn, causes the corresponding polymorphic behavior.
During puberty, a large number of hormones are released that ultimately determine biological differences by sex. During this period, boys 'level of testosterone increases 18 times, and girls' level of estradiol - 8 times.
In the absence or lack of germinal androgens during the corresponding critical period, sexual differentiation automatically, regardless of the chromosomal sex, occurs according to the female type. An example would be the development of a child in those cases when, due to the pathological influence of ecology (intoxication, radiation), the sex glands do not form (state of agonadism). On the other hand, if the mother during pregnancy takes drugs that stimulate the appearance of the male hormone (testosterone), then the female embryo can be “defeated”, which will later manifest itself in the masculinization of female behavior. Such girls prefer a society of boys and games peculiar to boys, they are self-confident and independent, that is, they are defined as tomboy. All this proves that androgens play a significantly larger role for intrauterine sex differentiation than estrogens.