Functional properties of nerve fibers innervating cutaneous corpuscles within cephalic skin of the Texas rat snake
| Autor: | Morris K. Jackson, Gernot S. Doetsch |
|---|---|
| Rok vydání: | 1977 |
| Předmět: |
Rat snake
Myelinated nerve fiber Maxillary nerve Snakes Stimulation Anatomy Adequate stimulus Biology Stimulus (physiology) biology.organism_classification Nerve Fibers Myelinated Texas Electrophysiology Nerve Fibers Dermal papillae medicine.anatomical_structure Species Specificity Developmental Neuroscience Neurology medicine Animals Integument Head Skin |
| Zdroj: | Experimental Neurology. 56:63-77 |
| ISSN: | 0014-4886 |
| DOI: | 10.1016/0014-4886(77)90139-x |
| Popis: | The functional properties of specialized cutaneous corpuscles found within the cephalic integument of the Texas rat snake were studied. The surface morphology of each of these end organs consisted of a rimmed, crater-like structure with a prominent peg protruding from the center of the crater. These surface features were directly associated with an underlying corpuscle which evaginated into the epidermis as a dermal papilla. The inner portion of the corpuscle contained a number of central cells with variously oriented cytoplasmic processes. Three or four myelinated nerve fibers were found near the base of the corpuscle; each fiber became unmyelinated as it entered the corpuscle and then divided into two or three smaller branches which terminated near the apex of the end organ. To determine whether or not these corpuscles might be specialized mechanoreceptors, the functional properties of 146 single maxillary nerve fibers innervating the corpuscle-rich supralabial scales of the Texas rat snake were studied. Twenty-one of these fibers (14%) were exclusively sensitive to mechanical stimulation of corpuscles, and were classified as “corpuscle units”; the other 125 fibers (86%) responded to mechanical stimulation of skin surrounding the corpuscles. Each corpuscle fiber was found to innervate from four to 13 individual corpuscles, with a mean of eight end organs per fiber. The adequate stimulus of these receptor units was lateral deflection of the central peg protruding from the crater of each corpuscle. Initial displacement of the peg from its vertical axis evoked a single “on” spike discharge; no response was elicited during sustained pressure exerted against the peg. When the peg was allowed to rebound to its original position, a single “off” impulse was usually elicited. Each fiber was optimally excited by moving mechanical stimuli across the surface of all corpuscles innervated by that fiber; the number of evoked spikes was directly related to the number of corpuscles stimulated. No directional preference for stimulus movement was found. All receptor units faithfully discharged one impulse during each cycle of a 256-Hz vibratory stimulus. Both the morphologic and electrophysiologic data indicated that the cutaneous corpuscles are structurally and functionally unique mechanoreceptors. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|