sex-linked inheritance

inheritance /in·her·i·tance/ (in-her´ĭ-tans)

1. the acquisition of characters or qualities by transmission from parent to offspring.

2. that which is transmitted from parent to offspring.

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cytoplasmic inheritance  mitochondrial i.

dominant inheritance  see under gene.

extrachromosomal inheritance  mitochondrial i.

intermediate inheritance  inheritance in which the phenotype of the heterozygote falls between that of either homozygote.

maternal inheritance  mitochondrial i.

mitochondrial inheritance  the inheritance of traits controlled by genes on the DNA of mitochondria in the ooplasm; thus the genes are inherited entirely from the maternal side, segregate randomly at meiosis or mitosis, and are variably expressed.

recessive inheritance  see under gene.

sex-linked inheritance  see under gene.

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sex-linked inheritance

n.

Inheritance that may result from a mutant gene located on either the X- or Y-chromosome.

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sex

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.

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sex cell

see germ cell, gamete.

sex chromatin

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.

chromosomal sex

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.

sex chromosomes

see sex chromosomes.

sex determination

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.

sex drive

see libido.

endocrinological sex

the phenotypic manifestations of sex determined by endocrine influences, such as mammary development, etc.

genetic sex

chromosomal sex.

sex glands

in the male includes the prostate, seminal vesicles, ampullae and bulbourethral glands; in the female includes ovaries.

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 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.

sex-linkage

includes X-linked (much the most common) and Y-linked loci.

sex-linked inheritance

see sex-linkage (above).

morphological sex

sex determined on the basis of the morphology of the external genitals.

neutrophil sex lobe

see drumstick lobe.

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.

sex parity

see sex ratio (below).

sex pheromone

see pheromone.

sex ratio

proportion of female to male births.

sex reversal

the sexual condition of animals in which gonadal sex and chromosomal sex are dissimilar.

sex steroids

steroidal compounds acting as hormones in reproductive processes; the principal ones are estrogen, progesterone, testosterone.