The metabolism of homogenates of the mouse epididymis.

This study has attempted a n evaluation of the in vitro metabolic characteristics of the epididymis of the mouse and a definition of areas for further research pursuant to the elucidation of the role of this organ in the process of sperm maturation and storage. Optimal conditions were ascertained for the manometric measurement of total respiration and for the estimation of glycoIytic activity by assay of lactate accurnulation and phosphate esterification in fluoride poisoned homogenates. Homogenates of mouse kidney were utilized in all experiments for comparative purposes. The in vitro data presented indicate the epididymis to be predominantly oriented to a glycolytic metabolism. It is suggested that this metabolic orientation when considered with the results of other investigators is compatible with a hypothesis for the secretion of lactic acid by the epididymal epithelium into the lumen of the epididymal canal for spermatozoan utilization. Although it has been established that mammalian spermatozoa undergo changes in their cytology, motility, metabolism and capacity for fertilization during their passage through the epididymis (Mann, '54; Maneely, '59), an inordinately small amount of work has been done on the role of the epididymis in this process. Some investigators (Braus and Redenz, '24) attributed to the epididymis a specific, but unknown, role in this "ripening" process; others (Young, '29a, b) have denied such an active function but all have agreed that in some way the epididymis is adapted for the long term storage of spermatozoa. Previous investigations of the mammalian epididymis have been predominantly of a descriptive nature. Those investigators who did choose an experimental approach were more concerned with the spermatozoa or the fluids in which these cells reside (cf. Salisbury and Lodge, '62). As a result, knowledge of the functional biochemistry and physiology of this tissue has been inferred rather than direct. A recent exception is the work of Annison et al. ('63) on the in vivo acetate and glucose metabolism of the Ram epididymis. As a basis for study of the metabolic characteristics of the epididymis, a comparison of the activity of homogenates of this tissue to activity observed in homogenates of kidney from the same animal was undertaken. Results from experiments with J. CELL. AND COMP. PHYSIOL., 66: 281-292. kidney could be compared to data in the literature and thus give assurance of reasonable results with the epididymal homogenates.