[Microscopic innervation of the spermatic ducts and testicle. IV. Testis]

The presence of nerve fibers in the testicle of the rat has been investigated both in light (silver and osmium-iodide impregnations, and histochemistry for acetylcholinesterase) and electron microscope. Nerve fibers were found in the albuginea and close to the intertubular blood vessels. However, these were not observed at ultrastructural level. On the other hand, the Leydig cells do not have a direct innervation but nerve fibers containing large and small granular synaptic vesicles were observed in the vicinity (3,000 A). The authors discuss the possible control of the testicular function by the peripheral nervous system.