Three-Dimensional Microanatomy of Mechanoreceptors and Their Possible Mechanism of Sensory Transduction

The study examined the fine structure of sensory nerve endings, specifically Ruffini endings in periodontal ligaments and longitudinal lanceolate endings around sinus hairs in rats, using scanning and transmission electron microscopy. Both receptor types displayed a triplet structure, known as the axon-Schwann cell complex, with specific modifications at their distal ends. The Ruffini endings coiled around collagen bundles, facilitating continuous transmission of tissue distortions, while the lanceolate endings were suspended in an amorphous matrix, allowing transient deflection during hair movement. The study proposed that the terminal tuft of Schwann cell processes and their accompanying axon fingers form a structural complex that potentially contributes to mechano-electric transduction.