Assessment of human sperm function after recovery from the female reproductive tract

The physiology and fertile life of human spermatozoa in the female reproductive tract have received little previous attention. A technique was developed for recovering spermatozoa from human cervical mucus at various intervals after artificial insemination. The functions of these cells as measured by penetration of the human zona pellucida and fusion with the zona-free hamster oocytes were examined. Penetration into the zona pellucida was consistently observed when sperm were recovered from 1 to 80 h after insemination. Penetration through the zona into the perivitelline space (PVS) was seen from 1 to 72 h after insemination. Fusion of human sperm with zona-free hamster oocytes was observed from 1 to 48 h after insemination. Motile sperm were recovered 112 and 120 h after insemination with swimming speeds comparable to freshly capacitated spermatozoa. Concentrations of recovered sperm at these longer intervals from insemination were insufficient for sperm-oocyte assays. These studies demonstrate that human spermatozoa aged in vivo may be recovered from cervical mucus for physiologic study, and suggest that the fertile life of human sperm may be 80 h or more.