The extrinsic innervation of the abdominal organs in the female rat

The extrinsic innervation of the abdominal organs in neonatal and adult female rats is described. Mainly an in toto acetylcholinesterase method was used; moreover, formaldehyde-induced fluorescence and acetylcholinesterase were demonstrated in sections. The major splanchnic nerve has its origin in the ninth and tenth thoracic sympathetic trunc ganglia. In the major splanchnic nerve a suprarenal ganglion is present. Sometimes the minor splanchnic nerve, arising from the tenth thoracic ganglion, joins the distal part of the suprarenal ganglion. The left and right major splanchnic nerves join the left and right celiac ganglia in the plexus. The left celiac ganglion is always bigger than the right one. The celiac plexus and the celiac inferior mesenteric plexus are joined by the intermesenteric plexus. Para-aortic nerves, originating in the caudal part of the thoracic sympathetic truncs, also join the abdominal prevertebral plexuses. The lumbar splanchnic nerves, not symmetrical in their origin, join the prevertebral plexuses and give off branches to the abdominal organs. The suprarenal glands receive bundles of nerve fibers, sometimes ganglionated, from the suprarenal ganglion. The kidneys are innervated from the celiac plexus, the upper lumbar splanchnic nerves and the intermesenteric plexus. The ovarian nerves are derived from the celiac plexus, the intermesenteric plexus and the upper lumbar splanchnic nerves. Bundles of nerve fibers run from the suprarenal ganglion in the celiac plexus in the direction of the suspensory ligament of the ovary. In many respects this description is at variance with existing literature on the autonomic innervation in the rat. These differences with the standard literature are relevant to those workers engaged in experiments on the sympathetic innervation of abdominal viscera.