title: The ultrastructure of the sensory nerve endings in the articular capsule of the knee joint of the domestic cat (Ruffini corpuscles and Pacinian corpuscles).
abstract: Two types of mechanoreceptor have been found in the articular capsule of the  knee joint of the domestic cat--Ruffini corpuscles and Pacinian corpuscles. Ruffini corpuscles are situated in the stratum fibrosum and consist of 2 to 6 cylinders. Each cylinder is made up of an afferent axon (diameter 3-4 micrometer), its swellings and terminal processes, Schwann cells enveloping the nerve swellings and terminal processes, endoneural connective tissue and a perineural capsule. The perineural capsule is incomplete in Ruffini corpuscles. The Pacinian corpuscles are 20 to 40 micrometer wide and 150-250 micrometer long. They are situated in groups of up to five at the boundary between the stratum synoviale and the stratum fibrosum. The afferent axon is myelinated (diameter 3-5 micrometer). Its terminal portion is inside the inner bulb which is formed of modified Schwann cells. Each corpuscle is enveloped by a perineural capsule (4-8 layers). The ultrastructure of the Pacinian corpuscles is compared with the ultrastructure of the skin receptors in the cat.
mesh_terms: D000818:Animals; D001699:Biometry; D002415:Cats; D006614:Hindlimb; D007596:Joints / Q000294:innervation*; D008465:Mechanoreceptors / Q000648:ultrastructure*; D010141:Pacinian Corpuscles / Q000648:ultrastructure*; D012867:Skin / Q000294:innervation; D013823:Thermoreceptors / Q000648:ultrastructure*