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THE INNERVATION OF THE OVARY, UTERINE TUBE, TESTIS AND EPIDIDYMIS By G. A. G. MITCHELL, CH.M. Lecturer on Anatomy, Aberdeen University THE innervation of the ovary and uterine tube resembles in many respects the nerve supply to the testis and epididymis. The nerves arise from three different sources: (1) A superior group from the intermesenteric nerves and from the renal plexus. (2) A middle or intermediate group from the superior hypogastric plexus (pre-sacral nerve) or from the hypogastric nerve. (3) An inferior group from the inferior hypogastric plexus (pelvic plexus). (1) The superior ovarian group. There are usually two main nerves in the superior ovarian group, an outer and an inner. The outer arises from the lower part of the renal plexus by two or more rootlets which coalesce to form a single nerve (Fig. 1). This nerve descends along the outer side of the ovarian vessels to the ovary, and may split up into two or three parts which are always connected by delicate branches to the ovarian nerves lying on the inner side of the vessels. The inner nerve of the superior ovarian group may arise in several ways. It may be attached to the lower end of the intermesenteric nerves and receive a filament from one of the lumbar splanchnic nerves (Fig. 1, left side), or to the upper end of the group of nerves which lies in front of the lower part of the abdominal aorta (abdominal aortic plexus) (Fig. 2). Sometimes it appears to arise from the upper end of the aortic bodies (Fig. 1, right side), which are so closely associated with autonomic nerves in infancy that it is impossible to separate them. In the adult small ganglia may be distinguished amongst the nerves overlying the lower part of the abdominal aorta, and it is probable that in or around the aortic bodies there are small autonomic ganglia which persist after the chromaffin tissue which forms the main mass of the aortic bodies has largely disappeared. Incidentally these bodies do not lie at the level of origin of the inferior mesenteric artery as is usually stated, but are below that level, their lower ends frequently overlying the origins of the common iliac vessels, and their upper ends reaching as high as the origin of the inferior mesenteric artery (Fig. 1). The inner nerve communicates near its origin with the branches of the renal plexus which arise from the lower ends of the intermesenteric nerves. Its rootlets unite to form a single nerve which converges towards the inner side of the ovarian vessels, and runs downwards with them. If it divides, one The Ovary, Uterine Tube, Testis and Epididymis 509 branch may pass to the outer side of the ovarian vessels, or lie between them, where it communicates or unites with the outer nerve (or nerves) of the superior ovarian group. In a previous article a direct connexion between the testicular nerves and the coeliac or superior mesenteric plexuses -was described, and a similar arrangement has been seen in a dissection of the ovarian nerves. The inner of the left superior ovarian nerves arose by two rootlets from the lower ends of the two outermost intermesenteric nerves on the left side, but it had another rootlet which passed upwards and became continuous with the commencement of the superior mesenteric plexus behind the neck of the pancreas (Fig. 1). Fig. 1. Strictly speaking, this branch connecting the coeliac or superior mesenteric plexuses with the ovarian nerves is really one of the intermesenteric nerves, but it merits special attention since it is unusual to be able to distinguish macroscopically such a direct connexion amidst the multiple intercommunica- tions of the autonomic nerves. The superior ovarian nerves give filaments both to the ovary and to the uterine tube, those to the tube being fine and not numerous. (2) The middle or intermediate ovarian nerves arise from the superior hypogastric plexusor the hypogastric nerve (Figs. 1, 2), being sometimes associated with a twig passing to supply the ureter. Two appears to be the 33-2 510 G. A. G. Mitchell common number, but in one dissection three nerves were seen, one arising from the superior hypogastric plexus, and two from the hypogastric nerve. The branch from the superior hypogastric plexus may arise directly, running close to the antero-internal aspect of the common and internal iliac vessels, or it may come via a nerve which arises from the superior hypogastric plexus, but lies behind the common and external iliac vessels. This post-arterial nerve, in addition to the ovarian branch, gives one or two twigs to the external iliac artery, and another twig usually enters the Psoas Major, either supplying Fig. 2. it or passing through it to unite with one of the branches of the lumbar plexus. Thereafter the nerve splits into several filaments which pass into the thigh alongside the'external iliac artery, where their further course has not been investigated'. The ovarian nerve itself, whether it comes directly or indirectly (in the way just described) from the superior hypogastric plexus, 1 Dr J. C. White, of Boston, who recently examined this nerve in three dissections, suggested that it may supply the femoral artery at the point where it gives off its profunda branch. Impulses from this region may play some part in the control of the blood supply to the lower limb. So far this interesting suggestion has not been verified as the limbs had been removed in all the specimens showing the nerve. The Ovary, Uterine Tube, Testis and Epididymis 511 passes downwards and outwards, finally breaking up into five or six terminal filaments which supply the ovary and the outer half of the tube. The lower of the middle ovarian nerves arises from the hypogastric nerve, and runs parallel and close to the other nerves described above (Fig. 2). It is usually smaller, and breaks up into filaments which supply the inner half of the tube, and possibly the ovary. In one dissection yet another but smaller nerve came off the hypogastric nerve; it supplied filaments both to the uterus and the inner end of the uterine tube. All these nerves lie along the postero-lateral wall of the pelvis until they reach the broad ligament. They then turn inwards between the layers of the ligament to reach the ovary, tube, and uterus. (3) The inferior ovarian nerves, three or four in number, arise directly from the hypogastric plexus or lower end of the hypogastric nerve (Fig. 1). They run upward between the layers of the broad ligament, one lying close to the uterine margin and to the anastomosis between the uterine and ovarian arteries, but the others lie at a distance from these vessels, nearer the side wall of the pelvis. They communicate by cross-branches, and are associated nearer their origin with the lowest ureteric nerves, while the innermost nerve of the group gives off tiny branches to the uterus. These nerves innervate the uterine tube, and are attached to its inner half, but delicate filaments can be traced outwards across the ampulla. None was detected entering the ovary. It is interesting to speculate as to whether the ovary and uterine tube receive a nerve supply from both parts of the autonomic nervous system, and if they do, whether the supplies are mixed up in the various nerves or are confined to separate pathways. By analogy with the hollow viscera it is almost certain that the uterine tube receives a supply from both sympathetic and parasympathetic, but a double innervation cannot be postulated with the same degree of certainty for the ovary. If the ovary does receive a nerve supply from both sympathetic and para- sympathetic, it is conceivable that both might come from above through the superior ovarian nerves, because the developing ovary draws down its nerve supply with it when it descends from the renal region to the pelvis. There is nothing to prevent its receiving a secondary nerve supply, which might contain both sympathetic and parasympathetic elements, from the pelvic plexus, yet no nerve filaments from this source could be detected entering the organ. Thus it is possible that, as in the case of the testis and epididymis, the ovary and oviduct may receive separate nerve supplies. But as the epididymis and uterine tube are not homologous structures any resemblance in the matter of nerve supplies, though interesting, is coincidental. If the above supposition is correct, then the entire ovarian nerve supply may be contained in the superior and middle ovarian nerves, and they would be more correctly termed superior and inferior ovarian nerves; those described as the inferior ovarian nerves would then be designated as tubal, or tubo- uterine, and not ovarian. If this possibility is accepted, the next problem 512 G. A. G. Mitchell that arises is the actual nature of the nerve-supply to the ovary, and by simple reasoning it can be deduced that the ovarian nerves must be mainly or even wholly sympathetic in nature, since sympathetic elements preponderate greatly in the upper abdominal autonomic plexuses-unless the organ receives an undue proportion of the available parasympathetic vagal fibres, compared with the other viscera supplied, which is unlikely. In making this statement it is assumed that the presence of parasympathetic fibres in the posterior nerve roots of the thoraco-lumbar spinal nerves has not been proved, and that the vagus carries the parasympathetic supply for most of the abdominal viscera. The uterine tube certainly receives a nerve supply from the hypogastric nerve and pelvic plexus, and it may receive delicate twigs from the superior ovarian nerves.

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