User:Kkio77/Intersex (biology)

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Intersex is a general term for an organism that has sex characteristics that intermediate between male and female. The term intersex typically applies to abnormal members of gonochoric species that are usually sterile. It is not to be confused with the term hermaphrodite.

Usually manifesting due to an abnormality during the embryological stage of development or on a more cellular level: sexual differentiation. Within human genetics, there are typically 22 autosomes and 1 sex chromosome- the X or Y. After fertilization, the genetic sex of an individual is determined. The same can be applied to other species, just different amounts of chromosomes. Intersex species on the other hand, are born with variations that differ from the standard XY and XX chromosome pairings. Pairings like YY, XXX, YYYY are all plausible for intersexual species.

Intersexuality has been reported in mammals, fishes, nematodes, and crustaceans. The most common form of intersexual organisms are gynandromorphs, where one side of an organism contains the sex organs of a female and on the same body, different side, contains the sex organs of a male.

Mammals[edit]

Intersex can also occur in non-human mammals such as pigs, with it being estimated that 0.1% to 1.4% of pigs are intersex.

Depending on the definition, the prevalence of intersex among humans have been reported to be about 0.018%. With the most common sex chromosome pairings as XXY and XXXY.

Nematodes[edit]

Intersex is known to occur in all main groups of nematodes. Most of them are functionally female. Male intersexes with female characteristics have been reported but are less common.

Fishes[edit]

Gonadal intersex also occurs in fishes, where the individual has both ovarian and testicular tissue. Although it is a rare anomaly among gonochoric fishes, it is a transitional state in fishes that are protandric or protogynous. Intersexuality has been reported in 23 fish families.

Crustaceans[edit]

The oldest evidence for intersexuality in crustaceans comes from fossils dating back 70 million years ago. Intersex has been reported in gonochoric crustaceans as early as 1729. A large amount of literature exists on intersexuality for isopoda and amphipoda, with there being reports of both intersex males and intersex females.