Electrophysiology of differentiating mouse spermatozoa.

The morphological aspects of spermatogenesis are well described in many mammalian species, but functional changes are not completely understood. Electrophysiological parameters were investigated in primary spermatocytes and early and late spermatids isolated from the seminiferous tubules of the mouse. Substantial changes were not detected in membrane potential between different developmental stages. Membrane potential was dependent on both potassium and sodium ion concentration gradients, but not on chloride gradients. The ratio of the permeabilities PNa/Pk varied according to the extracellular concentrations of sodium and potassium. Ouabain, a specific inhibitor of Na+, K+-activated ATPase, produced a maximal reduction in membrane potential of 20%. Comparisons were drawn between differentiating germ cells and previously determined properties of mature spermatozoa.