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Primary sexual characteristic - Definition


Primary sexual characteristics represent all genital organs that enable the differentiation of the male and the female in many species. In humans, they determine the sex at birth according to the external genitalia: a penis and testicles located in the scrotum for boys; the labia and vagina for girls. Some also consider the inner organs, in differentiating between men and women, among the primary sexual characteristics such as the prostate and seminal vesicles in men, and the ovaries, fallopian tubes, and uterus in women. They are distinguished from secondary sexual characteristics which are acquired later during puberty and hormonal development: hair, deepening of the voice, and increased muscle for men; and hair, breast development, milk secretion capacity, and the onset of menstrual cycles with periods for women.