Presence of intranuclear inclusions in the principal cells of the epididymis of the garden dormouse Eliomys quercinus L.

Globular inclusions are present in the nuclei of the columnar epithelial cells lining the ductus epididymidis in the garden dormouse, Eliomys quercinus L. Such inclusions have been reported in the dog where they are very abundant, in the stallion and in man. They have been found to be absent from sheep, cat, rabbit, guinea pig, rat and mouse. We have now found them in the garden dormouse, an ascrotal hibernator, but have been unable to detect them in another hibernator, the thirteen-lined ground squirrel Citellus tridecemlineatus, this time a scrotal mammal. The globular inclusions are first seen in the perinuclear space formed by the two membranes of the nuclear envelope; they are then invested by the inner membrane of the nuclear envelope and transferred into the nucleus. They later disintegrate and the vacuole is finally left with an electron-transparent content. The number of inclusions varies with the hormonal status of the animal: the granules are always present as soon as there is a rise in plasma testosterone. Electron energy-loss spectroscopy in the electron microscope (EELS) shows that inclusions contain C, N, O, Fe, Mg, P and S. This suggests that the intranuclear granules are made of protein cross-linked by disulphur bonds and contain iron, magnesium and phosphorus.