The vagina is a portion of the female reproductive tract, running from the cervix of the uterus to the exterior of the body. Tube-like in shape and highly elastic, it receives the erect penis during sexual intercourse. It has a ribbed lining that secretes a lubricating fluid during sexual arousal and intercourse. The muscular walls of the vagina enable it to dilate massively to allow the passage of a baby during birth.

Cross-section of the vagine. The passage is roughly H-shaped but widens during intercourse."