Histochemistry and ultrastructure of nerve fibres and contractile cells in the tunica albuginea of the rat testis.

Whole-mounted preparations of the tunica albuginea of the rat testis were studied using light microscopy techniques for demonstration of cholinergic nerve fibres (Karnovski-Root method), catecholaminergic nerve fibres (De la Torre's method) and actin filaments (avidin-biotin-peroxidase method). An ultrastructural study of different regions of the albuginea was also performed. Cholinergic fibres were seen to penetrate into the albuginea with the testicular artery to form a broad network in the mediastinum testis, many fibres ending beneath the rete testis epithelium. Catecholaminergic fibres penetrated through the middle part of the cauda epididymis and formed a plexus in the albuginea covering the inferior testicular pole. This plexus gave rise to straight fibres which formed varicosities, some of them appeared related with mast cells. Actin-containing cells were only found beneath the rete testis epithelium. These cells were similar to myofibroblasts. The location of both cholinergic fibres and contractile cells among the rete testis channels suggests that these cells may be involved in the pumping of semen towards the ductuli efferentes and that their contractility may be regulated by cholinergic fibres.