ENCAPSULATED NERVE END-ORGANS IN RABBIT, MOUSE, SHEEP AND MAN

There is a system of highly specialized blood vessels around each sensory hair follicle in the rabbit. The system includes two arteriovenous shunts and a cylinder of dilative blood vessels enclosed in a large bulbous capsule of connective tissue. The shunts, dilative blood vessels and capsule surround two cylinders of nerve fibers; together these structures constitute the largest neurovascular end‐organ in skin. The end‐organ is similar to the glomus‐Pacinian corpuscle complex in the hairless digital skin of man. The blood vessel cylinder and arteriovenous shunts in rabbit skin connect with a system of dilative blood vessels that are enclosed in another capsule of connective tissue under a small thick pad of sensory epidermis, beihnd the sensory hair follicle. The pad of epidermis contains expanded nerve fibers (Merkel's discs) that end near a cluster of Merkel (tactile) cells. In some regions of skin, each area of sensory epidermis is associated with the orifice of a sweat gland duct. In hairy skin of the rabbit, mouse and sheep, the areas of sensory epidermis, Merkel cells and Merkel's discs are distributed in parallel chains or in whorls and loops. Similarly, in the hairless skin of man the sensory epidermis, clusters of Merkel's discs and sweat duct orifices are distributed together in rows, whorls and loops that form the finger and palmer prints. In some regions of hairy human skin the same components occur together in small circular whorls called the Haarscheiben or Rosetten. Copyright © 1969 The Wistar Institute of Anatomy and Biology