First evidence of unicellular glands in the general epidermis of terrestrial reptiles

Abstract

The general integument of reptiles is traditionally defined as being dry, but we report here the discovery of unicellular mucoid glands (UCMG) in the dorsal skin of lizards of the genus Phelsuma (Gekkonidae). To this end, the skin of these lizards and of some others for comparison was studied by scanning electron microscopy and transmission electron microscopy. These photographs showed that the development and function of the UCMGs are related to the skin's sloughing cycle. The UCMGs differentiate at scattered locations from Oberhäutchen cells of the inner (new) epidermal generation, above the differentiating beta-keratin layer. While the inner generation matures, the UCMG increases in size; unlike the surrounding Oberhäutchen cells, it does not develop the spinules that characterize gecko skin. When, upon sloughing, the inner generation becomes the new outer generation, and the Oberhäutchen forms the skin surface, the UCMGs, several per scale, dot the surface as mucus-inflated "blebs" projecting from the surrounding spinulate Oberhäutchen, each nesting in a shallow pit of the underlying beta-keratin. On the surface, the UCMGs rupture and the mucus appears to dissipate in cords, flowing over the tips of the spinules, and incorporating minute foreign bodies. It is concluded that, due to the low wettability of the spinulate surface (derived from the spacing of the spinules), the cords brush off easily, with the mucus functioning as a cleaning agent.

Nocturnal foraging in a diurnal tropical lizard (Squamata: Gekkonidae: Phelsuma laticauda) on Hawaii

“…When possible, individuals were captured (by noose) after the observation, and were marked. Since individuals could not be marked with adhesive tape, due to mucus glands (Hiller & Werner 2008), we clipped half of one or two toes. Upon capture we recorded body (rectal) temperature (in some cases), air temperature (1 m above ground, in shade) and (sometimes) substrate temperature (Miller-Weber small-animal mercury thermometer); time; sex and location where the gecko had been.…”