Resorption and Secretion of Ions by the Epididymis

Abstract

Techniques of micropuncture and electron microprobe analysis have located ions within different compartments of the epididymis. There are increasing intraluminal sodium and potassium concentrations distally in tissue slices from the mouse epididymis (Hamilton et al., 1976). but these measurements would include the contributions from the increasing numbers of sperm cells. In other species during maturation in the epididymis the concentration of sodium ions within spermatozoa decline in parallel with removal of Na⁺ from the surrounding fluid and intracellular K⁺ in sperm is always maintained above that of epididymal fluid (Table 12). Ion concentrations in epididymal fluid differ markedly from blood or testicular fluid and regional differences are present (see Table 13); most noticeable are a loss of Na⁺ and an increase in K⁺ with high phosphate concentrations in the rat (Hinton et al., 1980a) and Mg²⁺ in the rabbit (Jones, 1978). Despite increased concentrations, a net resorption of potassium along the length of the duct is observed when the resorption of fluid is taken into account (Turner, 1984). pH decreases sharply between the testis and the caput epididymis of the rat (Levine and Kelly, 1978).