Innervation of hairs in the facial skin of marsupial mammals.

The innervation of pelage, guard hairs and vibrissae hairs was studied in five species of marsupial mammals by means of electron microscopy for the first time. This study showed that members of different superfamilies in marsupial mammals displayed the same pattern of hair innervation. This also resembled the pattern seen in the placental mammals. All types of hairs had both longitudinal and transverse lanceolate nerve terminals. Pelage hairs did not have any Merkel cells. Guard hairs were very richly innervated and had free nerve endings, lanceolate nerve endings, many Merkel cells with their associated nerve endings and pilo-Ruffini nerve endings. Vibrissae hairs had free nerve endings, Merkel nerve endings and lamellated corpuscles, but pilo-Ruffini nerve endings were not seen in this investigation. Because of the profusion and variety of innervation in guard hairs of the marsupial mammals, these hairs may have a similar function to vibrissae hairs in placental mammals.