[Intersexuality in the horse. Morphologic, hormone analytic and cytogenetic studies in an Arabohaflinger horse].

This article discusses a case of mammalian intersexuality, featuring an arabo-haflinger horse that has physical features and sexual behavior of both male and female. The researchers conducted morphological, hormonal, and cytogenetic studies to explain this phenomenon, theorizing that the condition arises due to a translocation of a Y-chromosome fragment containing the gene for the H-Y antigen into a genetically female horse.

Morphologic Studies

• The authors examined the external and internal genitalia of the horse. Externally, the horse had a mammary gland, a vulva, and what appeared to be an overly developed clitoris. Upon internal examination, the horse was found to have underdeveloped testes instead of normal female reproductive organs.
• The physical anomalies suggested intersexuality, a condition where an individual possesses physical sexual characteristics of both sexes, not aligning with their genetic sex. This is relatively rare in mammals.

Hormone Analytic Studies

• The researchers likely carried out tests to evaluate the horse’s hormonal profile, although the article abstract does not provide explicit details.
• As the horse displayed male-like sexual behavior, it is possible that it had atypical levels of sex hormones, possibly higher levels of androgens (male-sex hormones) than a genetically female mammal should possess.

Cytogenetic Studies

• A karyotype analysis was done on the horse. This process involves the visualization and counting of chromosomes in a cell. The karyotype analysis revealed a 64,XX pattern, which is typical of female horses.
• Despite the female karyotype, the presence of physical male attributes led researchers to theorize that a fragment of the Y-chromosome had been transferred to one of the female chromosomes.
• This probable translocation could carry the gene for the H-Y antigen, a factor involved in initiating male sexual development, thus leading to the development of the rudimental testes despite the animal’s genetic female sex.