Testes, epididymides, and vasa deferentia of rats were examined for the distribution of cholinesterases using the Koelle thiocholine method. Activity of these enzymes was studied from birth to maturity. Acetylcholinesterase appeared first in Schwann cells of the nerve plexus of the vas deferens and cauda epididymidis at birth. Epithelial cell pseudo-cholinesterase appears in the vas deferens at four days, and an adult distribution is attained at thirty days. Testis, rete testis, ductuli efferentes, and upper caput epididymidis are mainly negative for cholinesterases. In the remainder of the epididymis, three zones of intense epithelial cell reactivity are preceded by regions of lesser intensity. Smooth muscles of the epididymis are negative, but the vas deferens musculature reacts for pseudo-cholinesterase. The nerve plexus is positive for both acetyl-and pseudo-cholinesterase, and is confined to the corpus and cauda epididymidis and vas deferens. The increasing density of the enzymepositive nerves, and the cholinesterase reaction of the musculature distally suggests a probable inhibitory role in the regulation of smooth muscle function in these regions under normal conditions. The absence of an enzyme-positive innervation and the presence of a n enzyme-negative musculature of the caput is correlated with an active rhythmic contractility in this region, which gradually disappears distally.

Cholinesterase (ChE) distributions in the epithelial and smooth muscle cells and in the peripheral nervous plexus of the reproductive ducts of the male rat are dependent on male sex hormones. Castration results in establishment of a low maintenance level of apical enzyme activity in the epithelial cells; smooth muscles and the nerve plexus of the vas deferens and cauda epididymidis also show reduced enzyme reactions. Testosterone treatment restores the normal enzyme relations in the epithelium and smooth muscles. Estradiol is partially effective, but reaction intensities do not attain normal distrbutions and proportions. Reductions in relative numbers of ChE positive nerve plexus fibers and their enzyme reactivity, and recession to outer muscle layers occur in castrates, but better recoveries follow after testosterone than after estradiol treatments. The results are interpreted to be in agreement with other data relating to smooth muscle behavior and its neural and hormonal regulation. Epithelial cell differentiation is complete in testosterone treated castrates, but is incomplete in estradiol treated cases, although ChE synthesis and duct growth occurs in the latter.The histochemical distributions of cholinesterases in the testis, epididymis, and vas deferens were described previously for normal rats from birth to adult ages (Risley and Skrepetos, '64). The epididyma1 epithelium below the upper two zones of the caput epididymidis and into the vas deferens showed the presence of nonspecific cholinesterase, with varying intensities of enzyme reactions in several regions. Smooth muscles of the ductus epididymidis were negative but those of the vas deferens were reactive. A nerve plexus of the cauda epididymidis and vas deferens was prominently displayed by the enzyme reactions, and was positive for both acetylcholinesterase (AChE) and nonspecific cholinesterase (ChE). However, in the caput epididymidis, ductuli efferentes and testis, nerves could not be demonstrated to be associated with the duct walls using the Koelle ('51, '55) thiocholine methods.With the above information available for experimental considerations, the epididymis and vas deferens were examined for possible effects of castration and sex hormone treatments upon the occurrence and distributions of cholinesterases. Numerous enzymes of the mouse epididymis are hormone-dependent, as shown by Allen and Slater ('57, '61), and by Bern ('51) and Bern and Levy ('52) in the vas deferens and other accessory sex organs of the rat, rabbit, and guinea pig, and mouse. If development and synthesis of ChE are dependent on male sex hormones, it would be of interest to determine if epithelial and smooth muscle cells and the peripheral nerve plexus might be affected similarly or differentially in this respect, and in what ways. The ChE reactions of these tissues in untreated, and in testosterone and estradiol treated castrate are rats described in this paper. MATERIALS AND METHODSThe untreated normal young and adult male rats studied previously (Risley and Sk...

Specialized cells in the epithelium react for cholinesterases when tested by the Koelle thiocholine method. Their morphology and contiguity with cholinesterase-positive nerves suggests receptor function. Impulses originating from them might relate to sensations or muscular reflexes involved in micturition and ejaculation, or both. If they are effector units, special secretory, excretory, or absorptive functions are indicated for cells of probable neural origin.