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sex-linkageInheritance in which the gene for the condition is carried on one of the X or Y sex chromosomes. Recessive sex-linked conditions almost always affect males, are carried on the male X chromosome and thus cannot be transmitted directly from father to son. The best-known sex-linked recessive condition is haemophilia. Y-linked conditions are rare; the Y chromosome is very small and carries few genes.
1. the fundamental distinction, found in most species of animals and plants, based on the type of gametes produced by the individual or the category to which the individual fits on the basis of that criterion. Ova, or macrogametes, are produced by the female, and spermatozoa, or microgametes, are produced by the male. The union of these distinctive germ cells results in the production of a new individual in sexual reproduction.
2. to determine the sex of an animal.
the persistent mass of chromatin situated at the periphery of the nucleus in cells of normal females; it is the material of the inactivated sex chromosome. Called also Barr body.
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.
see sex chromosomes.
1. the change in the fetus to a male or female configuration; the process by which the sex of an organism is fixed, associated, in animals, with the presence or absence of the Y chromosome.
2. diagnosis of the sex of the fetus before birth performed by examination of fetal fluids obtained by amniocentesis.
sex determining region of Y
a single gene responsible for determining the sex of an animal.
the phenotypic manifestations of sex determined by endocrine influences, such as mammary development, etc.
in the male includes the prostate, seminal vesicles, ampullae and bulbourethral glands; in the female includes ovaries.
the sex as determined on the basis of the gonadal tissue present (ovarian or testicular).
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 and head, mammary development and the pitch of the voice. The male hormones stimulate production of spermatozoa, and the female hormones control ovulation, pregnancy and the estral cycle.
includes X-linked (much the most common) and Y-linked loci.
see sex-linkage (above).
sex determined on the basis of the morphology of the external genitals.
neutrophil sex lobe
see drumstick lobe.
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.
see sex ratio (below).
proportion of female to male births.
the sexual condition of animals in which gonadal sex and chromosomal sex are dissimilar.
steroidal compounds acting as hormones in reproductive processes; the principal ones are estrogen, progesterone, testosterone.