sex chromosomes

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Related to Gonosome: allosome

sex chro·mo·somes

the pair of chromosomes responsible for sex determination. In humans and most animals, the sex chromosomes are designated X and Y; females have two X chromosomes, males have one X and one Y chromosome In certain birds, insects, and fish the sex chromosomes are designated Z and W; males have two Z chromosomes, females may have one Z and one W chromosome, or one Z and no W chromosome.
Synonym(s): gonosome

sex chro·mo·somes

(seks krō'mŏ-sōmz)
The pair of chromosomes responsible for sex determination. In humans and most animals, the sex chromosomes are designated X and Y; females have two X chromosomes, males have one X and one Y chromosome.

sex chromosomes

The pair of chromosomes that determines gender. The other 22 pairs of chromosomes are known as autosomes. Women have two sex chromosomes of similar appearance called X chromosomes (XX). Men have one X chromosome and another, much smaller chromosome, called a Y (XY). Sperms have half the normal complement of chromosomes (haploid) and contain either an X or a Y. If an X chromosome effects fertilization the result will be a female, if a Y, a male.

sex chro·mo·somes

(seks krō'mŏ-sōmz)
The pair of chromosomes responsible for sex determination. In humans and most animals, the sex chromosomes are designated X and Y; females have two X chromosomes, males have one X and one Y chromosome.

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.

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
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.