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An abnormal individual, having some male and some female characteristics. Gyn [female] - Andro [male].

These characteristics can be seen in specimens, where both male and female characteristics can be seen physically because of sexual dimorphism.

A gynandromorph can have bilateral asymmetry, one side female and one side male, or they can be mosaic, a case in which the two sexes aren’t defined as clearly.

Bilateral gynandromorphy arises very early in development, typically when the organism has between 8 and 64 cells. Later the gynandromorph is mosaic.

The cause of this phenomenon is typically, but not always, an event in mitosis during early development. While the organism is only a few cells large, one of the dividing cells does not split its sex chromosomes typically. This leads to one of the two cells having sex chromosomes that cause male development and the other cell having chromosomes that cause female development. For example, an XY cell undergoing mitosis duplicates its chromosomes, becoming XXYY. Usually this cell would divide into two XY cells, but in rare occasions the cell may divide into an X cell and an XYY cell. If this happens early in development, then a large portion of the cells are X and a large portion are XYY. Since X and XYY dictate different sexes, the organism has tissue that is female and tissue that is male.

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