Oxygen tension of the vaginal surface during sexual stimulation in the human

An oxygen electrode was maintained by suction on the vaginal wall in seven women. The basal value of pO2 was 9.3 mm Hg +/- 10.7 (mean +/- standard deviation) before clitoral self-stimulation was initiated. When stimulation took place the oxygen tension rose and peaked immediately after orgasm to 39.5 +/- 14.1 mm Hg. It then declined and fell to 20.1 +/- 13.8 mm Hg 10 minutes after the peak value. The changes correlate closely with changes in vaginal blood flow. The increased oxygen tension may be one of the factors that enhance of even initiate the motility of spermatozoa when deposited intravaginally.