Epididymal storage at abdominal temperature reduces the time required for capacitation of hamster spermatozoa.

The epididymis was reflected unilaterally or bilaterally to the abdomen in adult hamsters, leaving normally functioning testes in the scrotum. In unilateral cases, spermatozoa taken from the abdominal cauda, 1 month or more post-operatively, underwent a reversal of head agglutination and dispersed earlier, and underwent hyperactivation and fertilized cumulus-free eggs about 30-45 min sooner than did spermatozoa from the contralateral scrotal cauda. In addition, spermatozoa from the abdominal cauda began to undergo a spontaneous acrosome reaction 30-45 min earlier and to a greater extent than in control spermatozoa. Finally, in females mated at or soon after ovulation, spermatozoa ejaculated by bilaterally cryptepididymal males fertilized eggs 30-45 min before those from normal males. Other females mated to bilaterally cryptepididymal males gave birth to normal litters. The results are considered in terms of the possibility that temperature-sensitive sperm-binding macromolecules, which may be involved in sperm storage in the cauda epididymis, could be one determinant of the need for capacitation.