Morphological Basis of Sensation in Hairy Skin

Abstract

Publisher Summary The hairy skin of a man, rat, and bat was investigated electron microscopically and histochemically, paying particular attention to the non-nervous components of the nerve endings and to the microtopography of the receptor organs. In the fine hairs, terminal branches of each myelinated axon, including the terminal spindles, were invested by a single branching Schwann cell. The endings exhibited strong cholinesterase activity. They were shielded from non-mechanical stimuli by their deep position, and by the overlying hair shaft and sebaceous glands. The papillary endings were derived from myelinated axons. They occupied the dermal papillae next to the hair orifices and gave a positive cholinesterase reaction. These endings may be involved in the reception of cold stimuli. The penicillate endings were primarily derived from non-myelinated axons. They gave a negative cholinesterase reaction and were poor in axoplasmic organelles. Each penicillus ramified over a large subepidermal area overlapping the area of adjacent penicilli. These endings appear to be associated with modalities that do not have punctate representation in the skin. As each penicillus is composed of a number of axons derived from several nerve cells, it may constitute a multimodal sensory package rather than a receptor associated with a single modality.