On the Innervation of the Testicle and Epididymis of 7-8 Month Human Fetus

Abstract

The innervation of the testicle and the caput epididymidis originate in the plexus spermaticus and that of the corpus and the cauda epididymidis in the plexus deferentialis. Between the two kinds of plexus only slight anastomosis is to be observed.The plexus deferentialis is formed in the vasa deferentialis, spreads to the cauda epididymidis and thence into the corpus epididymidis and turns into the plexus ductus epididymidis. The plexus spermaticus runs through the plexus pampiniformis and thence spreads into the caput epididymis and the testicle. In the former part it forms the plexus ductuli efferentis, but in the latter, it passes first over into the plexus mediastinalis testis and the largest part of its nerve elements runs thence into the tunica vasculosa and finally spread out into the interstitial connective tissue through the septula testis. A small part of the nerve fibres of the plexus mediastinalis testis, however, run through the rete testis into the parenchyma testis.The plexus ductus epididymidis is very well developed already in the later fetal stage and comes into frequent anastomosis with the perivascular plexus running along the blood vessels. The vegetative fibres always develop into preterminal fibres and thence into STOHR's terminal reticula, which come into control by contact over the smooth muscle cells. The development of the vegetative fibres is particularly powerful in the cauda epididymidis where the muscle layer of the ductus is well developed.The plexus ductuli efferentis is far poorer in development than the plexus ductus epididymidis, due to the poor development of the muscle fibres in this part. The vegetative fibres here too end in STOHR's terminal reticula, which run as far as into the membrana propria but not further in the epithelial cells of the ductuli. STOHR's terminal reticula are formed in the interstitial connective tissue of the testicle too, but in the fetal stage, they are far poorer in development than in human adults. The terminal reticula here stand in control by contact over the LEYDIG's cells.A small number of sensory fibres are found in the plexus spermaticus. These probably originate in the branches of the nn. sacrales running into the plexus hypogastricus.The sensory terminations found in the testicle and the epididymis, being originated in the sensory fibres running in the plexus spermaticus, are present in the testicle and the caput epididymidis, but scarcely in the corpus and the cauda epididymidis.The sensory fibres running toward the mediastinum testis seem to be somewhat more numerous than those directed toward the caput epididymidis. The former part from the vegetative fibres upon reaching the rete testis, run through the connective tissue lining the rete or between its ducts and end in unbranched and simple branched terminations. Their terminal fibres show frequent change in size and usually end in sharp points. Often they penetrate into the one-rowed epithelium of the rete and end as intraepithelial fibres.The above findings are not much different from those obtained in adult human specimens by YAMASHITA. Thus, the sensory terminations in these parts seem to reach nearly complete formation in the fetal stage. Not rarely are found sensory fibres running further beyond the rete testis into the tunica albuginea and forming their terminations there. In the parenchyma testis, however, no sensory termination has been found.In the corpus and the cauda epididymidis no sensory termination has been adequately ascertained, but in the caput epididymidis may be seen some unbranched and simple branched terminations similar to those found in the rete located in the interstitial connective tissue of the ductuli efferentes. But here no intraepithelial fibres as found in the rete testis are observed.