An ultrastructural study of the inner core of the Pacinian corpuscle

Abstract

SummaryPacinian corpuscles from the hindfeet and mesentery of cats have been examined by light and electron microscopy. The study focuses on the inner core region which houses the single, non-myelinated terminal of the afferent axon. This region of the axon possesses specialized axon processes which enormously increase the surface area of the axolemma. The axon processes are long, branched, filiform structures, containing exclusively ~6 rim microfilaments, and are reminiscent of filopodia on the tips of growth cones of axons and dendrites. These axon processes emanate from the two poles of the elliptical terminal axon, from several sites in the transitional zone, and from the entire surface of the ultraterminal axon, the bulbous, branched, distal extremity of the nerve fibre. Each branch of an axon process articulates with an inner core cell hemilamella except at the distal end of the ultraterminal where axon processes may also approximate the inner edge of the outer core. The base of each axon process contains an elaborate array of organelles including clear and dense-core vesicles of synaptic vesicle size, all enmeshed in ~6 nm microfilaments. The structure and location of the axon processes appear to be eminently suitable for detecting pressure transients transmitted through the outer core of the corpuscle. It is suggested that the mechano-electrical transduction system has, as its morphological substrate, multiple units, each formed by a branched axon process and its specialized basal region. The existence of sympathetic axon terminals abutting the central axon is disputed but the presence of unusual, dense-centred and elongated vesicles within cellular profiles close to the axon is confirmed.

Glial Growth Factor Rescues Schwann Cells of Mechanoreceptors from Denervation-Induced Apoptosis

“…Sensory terminals of Golgi tendon organs and Pacinian corpuscles are closely associated with Schwann cells. Although there is no direct evidence that the sensory terminals of these mechanoreceptors act as presynaptic release sights for synaptic vesicles, they have both dense and clear core vesicles (Spencer and Schaumburg, 1973;Z elená and Soukup, 1977;Zelená, 1978) and label with the synaptophysin antibody (also see De Camilli et al, 1988). Therefore, we used anti-synaptophysin in conjunction with anti-neurofilament to enhance labeling of the complete afferent nerve arborizations.…”

“…The sensory nerve endings of both of these mechanoreceptors are associated with Schwann cells (Spencer and Schaumburg, 1973;Z elená and Soukup, 1977;Z elená, 1978). Ultrastructural examinations of tendon organs suggest that terminal branches of the afferent nerve are covered by nonmyelinating Schwann cells (Z elená and Soukup, 1977).…”

“…Ultrastructural examinations of tendon organs suggest that terminal branches of the afferent nerve are covered by nonmyelinating Schwann cells (Z elená and Soukup, 1977). In the Pacinian corpuscle, layers of specialized Schwann cells wrap the afferent terminal (Spencer and Schaumburg, 1973;Z elená, 1978), and only a few of these cells participate in myelination of a portion of the axon (Z elená, 1978). Schwann cells associated with afferent endings of mechanoreceptors therefore appear similar to terminal Schwann cells, the nonmyelinating Schwann cells covering the motor axon terminal at the neuromuscular junction (Son et al, 1996).…”

The fine structure of lamellated nerve endings found in the rat gingiva.

“…PEASE and QUILLIAN (1957), CAUNA (1953, 1958), PEASE and PAILLIE (1959, CAUNA and Ross (1960), CHOUCHKOV (1971( ), HASHIM0T0 (1973, SPENCER andSCHAUMBURG (1973) andIDE (1976) all reported on the fine structure of the Meissner corpuscles and Pacinian corpuscles.…”

Electron Microscopic Histochemistry of Cholinesterase Activity of Vater-Pacini Corpuscle

“…The morphology of the Vater-Pacini corpuscle has been well documented by light (2,13) and electron microscopy (14,15,16,19) using primate hands or cat mesentery. The corpuscle consists of nerve ending, inner and outer cores and capsule.…”