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1. the fundamental distinction, found in most species of animals and plants, based on the type of gametes produced by the individual; also the category to which the individual fits on the basis of that criterion. Called also gender. See also gender identity and gender role.
2. to determine which of these categories an organism belongs in.
chromosomal sex the sex as determined by the presence of the XX (female) or the XY (male) genotype in somatic cells, without regard to phenotypic manifestations. Called also genetic sex.
endocrinologic sex the phenotypic manifestations of sex determined by endocrine influences, such as development of breasts and genital organs.
genetic sex chromosomal sex.
gonadal sex the sex as determined on the basis of the gonadal tissue present (ovarian or testicular).
sex hormones glandular secretions involved in the regulation of sexual functions. The principal sex hormone in the male is testosterone, produced by the testes. In the female the principal sex hormones are the estrogens and progesterone, produced by the ovaries. These hormones influence the secondary sex characters, such as the shape and contour of the body, the distribution of body hair, and the pitch of the voice. The male hormones stimulate production of spermatozoa in men, and the female hormones control ovulation, pregnancy, and the menstrual cycle in women.
morphological sex sex determined on the basis of the morphology of the external genitals.
nuclear sex the sex as determined on the basis of the presence or absence of sex chromatin in somatic cells, its presence normally indicating the XX (female) genotype, and its absence the XY (male) genotype.