FATE OF SPERMATOZOA IN THE UTERUS OF THE MOUSE AND RAT

Abstract

SUMMARY The uterine fluid of mice killed 2–6 hr after coitus and ovulation amounted to about 0·1 ml. and contained about 20 million spermatozoa and virtually no leucocytes. By 14–18 hr after coitus the leucocytes had increased to about 25 million and the spermatozoa had decreased to about 11 million, most of which were undergoing phagocytosis. Approximately 20 hr after coitus the uterine contents are apparently evacuated, in spite of the continued presence of a copulation plug. Phagocytosis of spermatozoa was also observed in rats but was much less extensive; this is considered to be because evacuation takes place sooner after ovulation, though still about 20 hr after coitus. The phagocytes were nearly all polymorphonuclear leucocytes. Leucocytic invasion of the uterine lumen seems to occur mainly because of the distension of the uterus with fluid and not because spermatozoa are present. No evidence was obtained that either spermatozoa or leucocytes pass from the lumen into the uterine wall.