Activité cholinestérasique des corpuscules sensoriels cutanés de Herbst et de Grandry

Cholinesterase activity of lamellated sensory corpuscles in the rat lip

Non-specific cholinesterase (ChE) activity was demonstrated in lamellated sensory corpuscles of the rat lip by light and electron microscopy using Karnovsky and Roots' method. ChE activity was present in the interlamellar spaces between neighbouring lamellae as well as in the peri-axonal space between axon terminals and their adjacent lamellae. Reaction products were also deposited in some caveolae of the lamellar cell plasma membrane, and in the cisternae of the rough endoplasmic reticulum as well as in the nuclear envelope of lamellar cell bodies. No reaction products were detected within the axon terminals. The findings show that the lamellated corpuscles in the rat lip, like other mechanoreceptors, have intense ChE activity which is probably synthesized in lamellar cells and released into the intercellular spaces. That ChE activity is particularly strong in mechanoreceptors composed of lamellar cells suggests that this enzyme would play an important role in function and/or maintenance of such mechanoreceptive corpuscles.

Cholinesterase activity of lamellated sensory corpuscles in the rat lip

Non-specific cholinesterase (ChE) activity was demonstrated in lamellated sensory corpuscles of the rat lip by light and electron microscopy using Karnovsky and Root's method. ChE activity was present in the interlamellar spaces between neighbouring lamellae as well as in the periaxonal space between axon terminals and their adjacent lamellae. Reaction products of ChE activity were also deposited in some caveolae of the lamellar cell plasma membrane, and in the cisternae of the rough endoplasmic reticulum as well as in the nuclear envelope of lamellar cell bodies. No definite reaction products were detected within the axon terminals. These findings show that the lamellated corpuscles in the rat lip, like other mechanoreceptors, have an intense ChE activity which is mainly associated with lamellar cells. It can be said that ChE histochemistry is useful to detect mechanoreceptors. The functional significance of ChE in mechanoreceptors is discussed.

The ultrastructure of Ruffini and Herbst corpuscles in the articular capsule of domestic pigeon

The present study identifies two types of sensory nerve endings in the articular capsule of the shoulder joint of domestic pigeons: Ruffini corpuscles (spray-like endings), and Herbst corpuscles. Ruffini corpuscles occur in the fibrous membrane of the articular capsule and consist of two to four branched cylindrical segments within a network of fascicles of collagen fibers. At the terminal ends of the cylinders the perineural sheaths of the capsule are deficient and surround the fascicles of collagen fibers. The axon terminals in each cylindrical segment of a Ruffini corpuscle repeatedly ramify, giving rise to delicate neurite profiles. These neurites and associated Schwann cells envelope small fascicles of collagen fibrils. Schwann cells cover only a part of the neurite profiles. The myelinated afferent axon enters the midregion of the cylinder and has a diameter of approximately 3 micrometer. Herbst corpuscles are situated in the subsynovial connective tissue and in the transition zone between the fibrous membrane and the muscular fascia. They appear as elongated ovals in longitudinal section and round in cross section. Small corpuscles measure approximately 5 micrometer x 200 micrometer in length and large ones approximately 100 micrometer x 600 micrometer. Each has a myelinated afferent axon (diameter 2.5--7.5 micrometer) that terminates in one to three inner cores. The inner core contains the nonmyelinated receptor portion of the nerve fiber surrounded by numerous cytoplasmic lamellae, a subcapsular connective tissue space, and a perineural capsule of eight to 12 layers. Avian joint receptors are similar to those present in the skin of various birds and Ruffini corpuscles resemble in fine structure equivalent receptors in joint corpuscles of the domestic cat.

Electron microscopic histochemistry of ATPase and alkaline phosphatase activities in mouse digital corpuscles

ATPase and alkaline phosphatase (ALPase) activities were histochemically examined in the sensory corpuscle of mouse digital pads at light and electron microscopic levels. ATPase activity was found on the plasma membranes of the lamellar cells. Moderate activity was present in the caveolae, but little activity could be demonstrated in the other portions of the plasma membrane. ALPase activity was found in the caveolae but not on other portions of the plasma membranes of the lamellar cells. ALPase activity was also observed on the nerve terminals. Neither ATPase nor ALPase activity was found on the pre-terminal portions of the nerve fibres. These findings indicate that the caveolae of the lamellar cells may be involved in a transport function and that the plasma membrane of the nerve terminals may have some permeability properties different from those of the pre-terminal portions of nerve fibres.