It has been known for many years that in certain animals, particularly rodents, a firm coagulated mass forms in the vagina after copulation. It was called a vaginal plug or copulation plug by Moore & Gallagher (1930) who described the anterior lobes of the prostate as the source of the coagulating enzyme and called these `coagulating glands'. This anterior portion differs physiologically and histologically from the middle and posterior lobes. In the albino rat the coagulating glands lie on the margins of the seminal vesicles, extending from their extremity to the base near the prostate.
Scott & Dziuk (1959) concluded that the coagulating gland in the albino rat was a major obstacle to electro-ejaculation since the plug blocked the urethra and caused death from uraemic poisoning. These authors removed the seminal vesicles and the