射精の研究
第3報 精液の Emission と射精時における内尿道口の閉鎖の神経支配について (I)
1971 年 62 巻 11 号 p. 877-886
詳細
1971 年 62 巻 11 号 p. 877-886
The nervous pathways controlling the two phenomena, seminal emission and closure of the internal urethral orifice were studied experimentally, using male mongrel dogs.
Methods: The nerves examined in this study were the nerve fibers entering the lower mesenteric plexus, the splanchnic nerves and the lumbar nerves. The peripheral cut end of these nerves was electrically stimulated continuously with pulses of 0.5-5V in amplitude, 0.5-2msec in duration and 1-40cps in frequency.
For seminal emission and ejaculation, posterior urethrogram was recorded by the method described in a previous report. For measurement of contraction of the internal urethral orifice, a latex balloon fitted at the tip of a No. 6 polyethylene tube was inserted into the internal urethral orifice and alteration of the pressure in the balloon was recorded.
The results obtained were as follows:
1) Selective Stimulation on the Nerve Fivers enterining the lower Mesenteric Plexus.
In this study the nerve fibers descending on the anterior wall of the aorta into the plexus were tentatively nominated as the central branch of the lower mesenteric plexus and the fibers entering from the lateral portion into the plexus as the lateral branch of the plexus.
When the central branch was stimulated, seminal emission occurred and contraction of the internal urethral orifice was not noted. On the other hand, when the lateral branch was stimulated, emission did not occur but the marked contraction in the internal urethral orifice was observed.
2) Stimulation of the Splanchnic Nerves.
Seminal emission was caused by stimulation of the greater splanchnic and the third lesser splanchnic nerves. The degree of emission was more remarkable on stimulation of the latter nerve. In regard to contraction of the internal urethral orifice, it was observed that when the 4th-6th lesser splanchnic nerves were stimulated the internal orifice contracted. In particular, contraction was most marked when the 5th lesser splanchnic nerve was stimulated. Accordingly, it was thought that seminal emission and contraction of the internal urethral orifice during ejaculation were controlled by the different nerve pathways upper the lower mesenteric plexus.
3) Stimulation of the Lumbar Nerves.
In this study, seminal emission was examined alone.
Slight emission was observed when the anterior roots of the 1st and 2nd lumbar nerves were stimulated. A remarkable emission was found to occur when the anterior root of the 3rd lumbar nerve was stimulated. Emission was not observed on stimulation of the other lumbar nerves and the posterior roots of the lumbar nerves.
