Microassay of sperm concentration in the rat epididymis by micropuncture technique.

Micropuncture samples taken from the rete testis, caput, corpus and cauda epididymidis of adult rats were assayed for intraluminal sperm concentrations. The amount of fluid resorbed from the efferent duct and epididymal lumen was calculated based on the sperm concentration. Epididymal sperm concentrations increased from the rete fluid to the cauda fluid through the caput fluid. Eighty-nine percent of the fluid leaving the rete testis is resorbed by the efferent ducts and proximal epididymal tubule, and 96% of the fluid leaving the rete testis is resorbed in the distal cauda epididymidis. Resorption is important for the control of intraluminal fluid by the epididymis.