Sensory receptors situated in the interphalangeal joint capsule of the fingers of the bonnet monkey (Macaca radiata).

Using bonnet monkeys (Macaca radiata) the content, location and types of sensory endings with regard to interphalangeal joints of the fingers of the hand were studied. Use of the modification of Barker and Ip [J Physiol (Lond) 1963;124: 476-488] of the de Castros silver method showed that the Paciniform/Pacinian corpuscles are almost the exclusive encapsulated receptors in this tissue. Free nerve endings are present. Using serial paraffin sections stained with the May-Grünwald-Giemsa stain, the proximal interphalangeal joint capsules were reconstructed. This confirmed the results of the study using teased preparations stained by the Barker and Ip method. In addition it was shown that the encapsulated endings were situated exclusively in the lateral and ventral aspects of the joint capsule. The number of lamellae of these encapsulated endings varied from as few as three to more than fifty. It is suggested that the contribution of these various receptors to kinaesthesis can depend on such factors as their relationship with tendons and skin.