The effect of rete testis fluid on the metabolism of testicular spermatozoa.

The O2 uptake of spermatozoa collected from the rete testis of conscious rams and boars has been measured polarographically either in the rete testis fluid (RTF) in which they were collected or in a synthetic saline medium (S-RTF) made to resemble the ionic composition of RTF as closely as possible. In both species, O2 uptake of the testicular spermatozoa was higher in RTF than in S-RTF. The addition of some of the organic constituents of RTF was without effect on O2 uptake. Pyruvate, lactate, acetate or alanine increased the O2 consumption of ram spermatozoa in S-RTF. Lactate had no effect on but acetate increased the O2 consumption of pig testicular spermatozoa. Phospholipid phosphorus and fatty acids decreased during incubation of ram spermatozoa in RTF and S-RTF. The addition of substances which increased the O2 consumption of the spermatozoa in S-RTF was without effect on the lipid composition. The fatty acid composition of the phospholipids and the proportions of the various phospholipids were unaffected by incubation. These results indicate that rete testis fluid has an appreciable effect on the metabolism of the spermatozoa it contains, and that this effect cannot be mimicked by any of the known organic constituents of the fluid.