Title: The number of spermatozoa in spontaneous ejaculates of rats
Abstract: Spontaneous seminal discharges are known to occur in many mammals, including rats (Orbach, 1961; Kihlström, 1966), hamsters (Beach & Eaton, 1969) and guinea-pigs (Martan, 1968). After such ejaculations the semen rapidly coagulates and if the animals are prevented from grooming the genital area it is possible to collect all the ejaculates delivered. It is known that there is a diurnal variation in spontaneous seminal discharge (Kihlström, 1966), and that there is a sharp decline in frequency of seminal emission following sexual activity in the rat (van Dis & Larsson, 1970; Beach, 1975). The presence of spermatozoa in spontaneous ejaculates has been confirmed by Orbach (1961) but there are no observations as to the number of spermatozoa in the spontaneous ejaculates, probably because of the difficulty of counting spermatozoa in the coagulated ejacula. Using a modification of the method of Freund (1958) for dissolving coagulated rat semen I have counted spermatozoa in the spontaneous ejaculates from Sprague–Dawley and Wistar rats.