Fine structure of the cutaneous nerve endings in the mole snout.

The fine structure of the nerve endings in the glabrous skin of the mole snout (Eimer's organ) were studied by light and electron microscopy. There are three types of nerve endings in the mole snout skin: free nerve endings, Merkel cells and encapsulated endings. 1. When nerve fibers enter the epidermis, they lose their myelin sheath. The basement membrane of the Schwann cell fuses with that of the epidermis. Some axons pass through the intercellular spaces between keratinocytes and terminate as the free nerve endings at the upper part of the stratum spinosum or the stratum granulosum. Expansions of the axons were often observed in the epidermis. Such expansions contain masses of mitochondria, large number of vesicles and neurofilaments. 2. Merkel cells are present near the basal portion of Eimer's organ. This cell is characterized by the presence of a number of moderately electron opaque granules ranging