Functional development of the tactile pad receptor system
| Autor: | P.H. Craig, H. Kasprzak, Daniel N. Tapper |
|---|---|
| Rok vydání: | 1970 |
| Předmět: |
Receptor complex
Time Factors Sensory Receptor Cells Neural Conduction Action Potentials Sensory system Biology Nerve Fibers Myelinated Nerve conduction velocity Developmental Neuroscience Methods medicine Animals Neurons Afferent Receptor Skin Histological examination Age Factors Laminectomy Anatomy Electric Stimulation Functional development medicine.anatomical_structure Tactile pad Animals Newborn Neurology Touch Cats Merkel cell |
| Zdroj: | Experimental Neurology. 26:439-446 |
| ISSN: | 0014-4886 |
| DOI: | 10.1016/0014-4886(70)90140-8 |
| Popis: | Development of the structure and function of the tactile pad sensory unit of the cat was studied during the first 7 weeks after birth. The epidermal pads were found in greatest density (200/cm2) at birth. The number of pads per primary afferent (one to four) was similar to that observed in the adult. The number of afferents and spatial distribution in the adult appeared to be fixed at birth; the number of pads normalized by skin area showed no significant change with age. Pad diameters were small at birth (120 μ) and approached the adult size (200 μ) by the seventh week Histological examination of pads revealed few or no Merkel cells at birth and during the first week. They appeared suddenly in the second week. Responses recorded from the primary afferent demonstrated that at birth the receptor was selectively sensitive to short-duration mechanical pulses (4 msec) at the low displacements seen in the adult (5–20 μ). The capacity to respond to repetitive stimuli, (1:1 at 200 Hz for 1 sec) was lowest at birth. An improvement in this capacity appeared to be correlated with the occurrence of Merkel cells rather than with an increase in fiber conduction velocity. In contrast to the evidence from regeneration studies of others, these data suggest that Merkel cells contribute to the sustained response rather than to selective sensitivity of the receptor complex. |
| Databáze: | OpenAIRE |
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