Sex reversal in chickens (Genetics)
Most cases of spontaneous sex reversal are the
result of a disease condition which has resulted indamage to the left ovary. Typically, female chickensonly have one functional ovary, the left one. Theright ovary and oviduct are present in the embryonicstages of all birds, but typically do not develop inchickens.In general, spontaneous sex reversal has beendescribed as the result of pathological conditions(e.g., ovarian cyst or tumor, diseased adrenal glands)which cause the left ovary to regress. Residual tissuein the right ovary proliferates in the absence of afunctional left ovary. This regenerated right gonad isknown as an ovotestis and may contain tissuecharacterisitics of the ovary, the testes, or both.There are reports of these ovotestes producing semencapable of fathering offspring. Most, however, willnever lay an egg or sire offspring.The "ovotestes" are steroidogenically functionaland secret androgens, as well as estrogen. As a result,the bird develops male secondary characteristics. Sowhile the bird is genotypcially female, it will bephenotypically male.
