Abstract

PIP: Extracts of washed spermatozoa from hamster and guinea pig cauda epididymidis and of human ejaculated sperm were all found to stimulate the motility of unwashed hamster epididymal spermatozoa in vitro, and to support development of fertilizing ability. The motility of hamster spermatozoa was only sustained in the presence of both sperm extracts and appropriate energy substrates, indicating a synergistic effect of the motility-stimulating component of the sperm extracts with energy sources. Albumin was also required for the development of fertilizing ability by hamster sperm. Comparison of different combinations of energy substrates indicated that pyruvate was the most important energy source for sperm motility and the acrosome reaction, but glucose and lactate played suporting roles. In all 3 species examined, the component of the sperm extracts that was responsible for stimulating hamster sperm motility was found to be heat-stable and to have the same elution volume on a Sephadex G-10 column, with an estimated molecular weight of about 200. These properties are identical to those of the sperm motility-stimulating factor found in blood serum and adrenal gland, suggesting that the active components may be similar or possibly the same.