Sensory Innervation of the Hairs of the Rat Hindlimb: A Light Microscopic Analysis

The study investigated the sensory innervation of hair follicles in the rat hindlimb using the Winkelmann silver technique. It found that small vellus hairs, common above the ankle, were often not innervated, while those that were had lanceolate terminals and circumferential Ruffini complexes. Guard hairs, more frequently innervated, had 3-15 afferents forming palisades and circumferential terminals. Rare tylotrich hairs, found above the ankle, were densely innervated with a prominent nerve forming a bilaminar arrangement of terminals. Differences in hair type distribution, innervation density, and growth cycle phase across different hindlimb regions suggested significant implications for somatosensory processing of hair-generated afferent input.