Innervation of the monkey vas deferens.

Fluorescent and acetylcholinesterase-positive cell bodies occur in the connective tissue surrounding the prostatic end of the monkey vas deferens. At both the testicular and prostatic ends, noradrenergic nerve fibres are distributed mainly in the smooth muscle coats while acetylcholinesterase-positive fibres are most densely distributed in the lamina propria but also quite significantly in the inner part of the smooth musculature. The percentage of cholinergic varicosities (containing a predominance of small agranular vesicles and some large granular vesicles) is higher in the smooth muscle coat than in the lamina propria at both the testicular (9.1% against 1.5%) and prostatic (19.38% against 5.16%) ends of the vas deferens and the percentages of cholinergic varicosities in both the lamina propria and smooth muscle coat (5.16% and 19.38% respectively) at the prostatic end are higher than those (1.5% and 9.1% respectively) at the testicular end. The percentage of noradrenergic varicosities (containing a predominance of small granular vesicles interspersed with some large granular vesicles and agranular vesicles) in the muscle coat is higher at the testicular (56.72%) than the prostatic (39.73%) end. In addition to cholinergic and noradrenergic nerves, varicosities resembling purinergic nerve fibres, varicosities containing flattened vesicles and sensory terminals are also present. In nearly all cases where no collagen fibres intervene between an axon varicosity and the smooth muscle membrane, the interval between the two is less than 180 nm, and may be as little as, or even less than, 20 nm. Lastly, close nerve-mast cell and nerve-fibroblast contacts have been observed.