Sexual differentiation in humans .

January 13, 2021 By Swapnil Suryawanshi

Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following gonadal determination.Sexual differentiation includes development of different genitalia and the internal genital tracts and body hair plays a role in gender identification.

Sex determination :

Main article: XY sex-determination system

Chromosomal sex is determined at the time of fertilization; a chromosome from the sperm cell, either X or Y, fuses with the X chromosome in the egg cell. Gonadal sex refers to the gonads, that is the testis or ovaries, depending on which genes are expressed. Phenotypic sex refers to the structures of the external and internal genitalia.

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External genital differentiation :

Photograph of an adult female human and an adult male. Note that both models have partially shaved body hair.

Males become externally distinct between 8 and 12 weeks, as androgens enlarge the phallus and cause the urogenital groove and sinus to fuse in the midline, producing an unambiguous penis with a phallic urethra, and a thinned, rugated scrotum. Dihydrotestosterone will differentiate the remaining male characteristics of the external genitalia.