THE CAT PUDENDAL NERVE - AFFERENT-FIBERS RESPONDING TO MECHANICAL STIMULATION OF THE PERINEAL SKIN, THE VAGINA OR THE UTERINE CERVIX

Some afferent fibers from the pudendal nerve of the female cat were st imulated by pressing on the perineal skin, the vagina or the uterine c ervix. Three different types of skin mechanoreceptors were found: (1) with low threshold (< 20 mg) and slow-adapting discharges; (2) with hi gh threshold (0.1-0.5 g) and slow-adapting discharges; and (3) with lo w threshold and fast-adapting discharges. Most of these receptors incr eased their firing frequency as the velocity of skin indentation was i ncreased (velocity detectors). The average conduction velocity of the skin afferents was 29 +/- 9 m/s. The receptors located at the vagina s howed a fast-adapting response to probing and were sensitive to the ve locity of the probe movement. Most of these receptors, however, showed a slow adaptation when the vaginal wall was distended with a balloon. The conduction velocity in vaginal afferents was 37 +/- 16 m/s. Those receptors responding to pressure on the uterine cervix adapted slowly to constant pressure but were sensitive to the velocity of the pressu re pulses. The conduction velocity in the afferents from the uterine c ervix was 31 +/- 9 m/s.