All XX Spanish Moles have ovotestes (both ovarian & testicular tissue) and make Eggs & Testosterone, but XY moles only have testes & Make Sperm. (Gender Showcase, 9-12)

Talpa occidentalis (mole, Iberian peninsula)

All females have ovotestes (ovotestes are gonads containing both ovarian & testicular tissue) XX have ovotestes & make eggs and testosterone only, XY have testes only and make sperm only.

Image caption: A Spanish blind mole emerges from underneath a rock. Photo credit (C) Tiago Magalhães.

Most gender-gene committees, with or without the presence of SRY, pass a resolution creating only a testis in males and only an ovary in females. In some species, though, even this most elemental aspect of bodily gender has been given a different configuration.

Among Talpa occidentalis—another burrowing mammal, an old world mole from the Iberian peninsula—all females have ovotestes, gonads containing both ovarian and testicular tissue. The ovotestes occur at the site in the body where simple ovaries are found in other species. 

Talpa XX individuals have ovotestes and make eggs in the ovarian part of their ovotests. They don’t make sperm, but they do have both sperm-related and egg-related ducts. The testicular part of these ovotestes secretes testosterone. XY individuals have testes only and make sperm.

References

  • R. Jiménez, M. Burgos, A. Sánchez, A. Sinclair, F. Alarcón, J. Marin, E. Ortega, and R.D. de la Guardia, 1993, Fertile females of the mole Talpa occidentalis are phynotypic intersexes with ovotestes, Development 118:1303-11.

  • Roughgarden p. 202