The digging behavior and skin differentiations in Heterocephalus glaber

The topography and histology of the skin of the naked mole (Heterocephalus glaber) have been correlated with its behavior. The integument is exceptionally loose, thereby reducing integumentary stresses when the animal is digging and moving in narrow tunnels. It also allows the position of the nasolabial sensory patch to change. This patch is exposed to mechanical stimuli when Heterocephalus moves along the tunnel, but becomes partially shielded by a transient buccal evagination, the formation and function of which are here described. Most of the differentiated patches of the skin lie in the cranial and anogenital regions. The eyes are microphthalmic and nearly completely closed by the nonmobile eyelids; there is no pinna, hair-coat or sweat glands. The epidermis is of variable thickness; in some places it has only one layer of cells. The detached epidermal cells penetrate the dermis irregularly. The epidermis of Heterocephalus is specialized by modifications of its germinative stratum, equivalent to an epidermosis, the syndrome of which consists of reduction of all types of epidermal buddings-pilogenetic and adenogenetic-as well as those which have a mechanical significance.