Significance of the Extracellular Matrix for the Regeneration of Sensory Corpuscles, with Special Reference to Pacinian Corpuscles

Abstract

The Pacinian corpuscle consists of an axon terminal and specialized non-neuronal cells of an inner and an outer core (Pease and Quilliam, 1957; Nishi et al., 1969; Munger, 1971; Halata, 1977; Chouchkov, 1978; Malinovsky and Pac, 1982). The inner core is formed by densely packed thin cytoplasmic processes (lamellae) of lamellar cells which surround the axon terminal in a bilaterally symmetrical fashion. These inner core lamellar cells are thought to be derived from Schwann cells. There are thin spaces between neighboring lamellae, in which an extracellular matrix including basal lamina-like material and fine collagen fibrils is present. The outer core is composed of loosely piled layers of thin cells concentrically encircling the inner core. There are definite basal laminae on these outer core cells and thin processes. The outer core cells are extensions of the perineural epithelial cells of the innervating nerve (Shanta and Bourne, 1968). The axon terminal is characterized by an accumulation of mitochondria beneath the axolemma and by small cytoplasmic processes (axonal spines) emanating from the axolemma (Munger et al., 1987; Ide et al., 1987a). It has been demonstrated that basal laminae can serve as conduits for regenerating axons in the peripheral nerve (Ide et al., 1983; Osawa et al., 1986). As described above there are extracelluar matrices containing basal lamina-like material in the inner core of Pacinian corpuscles.