In vivo and in vitro studies with different parts of the epididymis and vas deferens were carried out to determine their inherent capacity to synthesize steroids and to correlate with the endogenous levels with or without the administration of hCG. Incubation with 14C-labelled pregnenolone and testosterone demonstrated that caput epididymidis was more active than other parts in synthesizing testosterone from 14C-pregnenolone and in converting labelled testosterone to 5 alpha-dihydrotestosterone (DHT). The cauda epididymidis and vas deferens accumulated more radioactivity in progesterone and dehydroepiandrosterone (DHEA) than the caput epididymidis. The levels of DHT, testosterone and 4-androstene-3, 17-dione in the caput epididymidis were reduced after ligation of ipselateral efferent ductules indicating the testicular origin of these steroids. The cauda epididymidis and vas deferens had higher levels of progesterone as compared to the other regions of the epididymis, which were decreased after the ligation. Intravenous injection of hCG increased the levels of oestradiol-17 beta in all tissues and markedly in the cauda epididymidis and vas deferens. The high levels of progesterone and oestradiol-17 beta present in these organs may be of importance in maintaining fertilizing ability of spermatozoa stored in the cauda epididymidis and vas deferens and their transport.

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Fresh ejaculates of bonnet monkeys were separated into fractions rich with highly motile and sluggishly motile spermatozoa. The motility, ability to fertilize zona-free hamster eggs, and distribution of testosterone-binding sites on spermatozoa were assessed to determine the relation between these sperm functions. Two parameters of objective assessment of motility-velocity and degree of flagellar bending-were significantly correlated with the ability to form pronuclei in zona-free hamster eggs. Only spermatozoa with good motility could form pronuclei, which might be important for assessment of the fertilizing ability. The motility was directly related to the distribution of testosterone-binding sites; the fraction having mostly motile spermatozoa was distributed over the sperm surface. The technique is simple and may be used to evaluate semen of nonhuman primates.

The presence of different hormones on the surface of ejaculated spermatozoa was determined by immunofluorescence studies of the binding patterns of specific antisera to these hormones. There were striking similarities in the binding pattern of antisera to steroid hormones found on human and monkey spermatozoa. Assuming the intensity of fluorescence is proportional to the concentration of the hormone, concentrations of testosterone on the acrosomal and the postacrosomal regions were higher than levels of progesterone and estrogens. Spermatozoa with a “tapering head” had more hCG bound on the acrosomal and postacrosomal regions than spermatozoa with “normal head” (oval shaped). Correlating these findings to the functions of spermatozoa will require further studies.

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