Sex-determination system

A sex-determination system is a biological system that determines the sex of which an organism will become a member, usually a genetic mechanism based on the chromosomes of that organism.

The most familiar sex-determination system is the XY sex-determination system found in human beings and other mammals. In the XY sex-determination system, females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY). There can also be other, abnormal, cases: see the chromosome article for information on abnormalities of the XY sex-determination system, and the intersexual article for information on variations in human sexual forms.

The WZ sex-determination system is found in birds and some insects and other organisms. In the WZ sex-determination system, the situation is reversed: females have two different kinds of chromosomes (WZ), and males have two of the same kind of chromosomes (ZZ).

Other sex-determination systems

Many other exotic sex-determination systems exist.

• Swordtail fish?
• etc

This is a stub article, and needs lots of tender loving care from people who know about this stuff

See also:

• testis-determining factor
• SRY

External links:

• The Unusual Sex Determination System of Chironomus
• The Enigma of Sex Determination in Reptiles
• Sex Determination and Differentiation
• http://www.alumni.caltech.edu/~copeland/work/fish.html
• http://www.ncbi.nlm.nih.gov/disease/SRY.html