On the intrinsic innervation of the epididymis of the camel (Camelus dromedarius).

The innervation of the camel epididymis was studied in 26 apparently healthy, sexually mature animals aged between 4 and 12 years. The material was collected during the different seasons of the year. Generally, five samples were taken from each epididymis. To demonstrate the general innervation pattern, immunohistochemical reactions to protein gene product-9.5, neurofilaments and neuron-specific enolase were used, in addition to acetylcholinesterase histochemistry. The nerve supply of the epididymis comes from two sources: (1) The majority of fibers come from the N. spermaticus inferior and accompany the deferent duct. (2) Another contribution stems from the N. spermaticus superior and enters the head region of the epididymis. From the exterior, the nerves penetrate the capsule of the organ to reach the interductular connective tissue. The terminal ramifications are observed directly within the wall of the duct and the wall of the epididymal arteries. The veins of the camel epididymis are not innervated. In the wall of the ductus epididymidis, the nerve fibers form plexuses at the subepithelial level and in the muscular coat. The amount of nerve fibers increases from the head to the tail, paralleling an increase in the intrinsic musculature. The intramural and interductular innervation of epididymal body and tail shows clear seasonal variations: More fibers and stronger reactions are observed during the winter season; the lowest density and the weakest reactions occur during the summer season. All epididymal nerves of the camel are unmyelinated. The majority of the intramural fibers and all in the arterial wall represent postjunctional sympathetic axons, but in the intramural plexuses of the duct a considerable number of cholinergic fibers are also present. Neuropeptide Y is the most frequent peptidergic transmitter and generally co-localized with dopamine-beta-hydroxylase in the sympathetic axons. Vasoactive intestinal polypeptide has a distribution similar to that of the cholinergic fibers. Calcitonin gene-related peptide-positive axons occur in moderate numbers, but never in the arterial innervation. Together with the relatively rare substance P-containing fibers, the calcitonin gene-related peptide-positive axons seem to represent the only sensory nerves in the camel epididymis.

Immunohistochemical investigations of the autonomous nerve distribution in the testis of the camel (Camelus dromedarius).

The distribution of autonomous nerves in the testis of the camel was studied by immunohistochemical methods. A total of 26 testes was collected during the different seasons of the year. As pan-neuronal markers, antibodies to protein gene product 9.5 and to neurofilaments are superior to antibodies against neuron-specific enolase and acetylcholinesterase histochemistry for the description of the nerves in the camel testis. Testicular nerves reach the camel testis by three access-routes as (1) funicular contribution, (2) mesorchial contribution and (3) as caudal contribution. The main target for testicular nerves is the arterial vascular tree of the organ, whereas all veins of testis and pampiniform plexus are devoid of any innervation in the camel. In the wall of the arteries, the nerves form a plexus at the media-adventitia border. The density of the arterial plexuses increases along the vascular tree: smaller septal and mediastinal arteries are better innervated than albugineal arteries and the latter better than the A. testicularis. The nerves in the septula testis, in the mediastinum and between the Leydig cells show clear seasonal changes, being particularly abundant in autumn and particularly scarce in spring. The nerves that reach the camel testis are unmyelinated and represent in the vast majority postjunctional sympathetic neurons. Cholinergic fibers are absent in the camel testis. Neuropeptide Y is the dominating peptidergic transmitter in the testicular nerves and colocalized with noradrenaline in the same axons. Vasoactive intestinal polypeptide-containing fibers reach the camel testis exclusively as parts of the caudal nervous contribution via the ligamentous bridge between testis and epididymal tail and are restricted to the caudal pole of the testis. Calcitonin gene-related peptide-positive axons are not frequent in the camel testis; nevertheless, they seem to be the most important sensory pathway of this organ.