Most mammalian chromosomes dictate their sex-identity with X and Y chromosomes. XX is female, XY is male, including in humans. However, in nearly six species of moles, XX females have been found with a hybrid of ovaries and testes known as ovotestes.

The testes arent fully functional. They cannot produce any sperm but they can release very high levels of testosterone (male-associated hormone). As a result, these moles become excellent diggers which helps them with their underground life.

The puzzle for scientists is how these male reproductive tissues are being formed in female moles even without the Y-chromosome. The answer is probably to look at the regions which control the genes instead of the genes themselves. The study was published in journal Science.

The female Iberian mole can be considered as intersex, as it has both male and female reproductive tissue. However, she develops a vagina only during the mating season and has functional female organs.

With most animals, males fertilize the egg produced by a female. However, 1% of humans can be born intersex. Other species like snails, earthworms, slugs etc can be hermaphrodite i.e. fully developed male and female reproductive parts.

The mole, however, feels different from them all, she has a male-looking external genital with a clitoris that looks like a penis. And for the most part of her life, the vaginal canal has no opening. While the testosterone production low in mating season, it can be higher than XY males for the rest of the year in these intersex moles.

At a certain point, sexual development usually progresses in one direction or another, male or female, explained Daro Lupiez, Geneticist at Max Planck Institute. However, they want to study how the evolution of these animals modulates sexual behaviour. The team theorizes that the ovotestes suggest some other gene must be active in the females, one that is not found on Y chromosome. The gene responsible for producing male hormones is CYP17A1.

They observed that it was present three times in the female moles genome instead of one. The triplication appends additional regulatory sequences to the gene which ultimately leads to an increased production of male sex hormones in the ovotestes of female moles, especially more testosterone, explained Francisca Martinez. She is the lead author of the study from the Institute for Medical Genetics and Human Genetics in Berlin.

Studies like these are important to normalise the existence of intersex individuals, even in humans, who are generally pathologized.

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Female Moles Have 'Ovotestes' that Produce Testosterone That Make Them Excellent Diggers - News18

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