Output of Spermatozoa and Fluid by the Testis of the Ram and Its Response to Oxytocin

Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545, U.S.A. (Received 12th July 1974) The space between the internal and external lamellae of the boundary tissue surrounding individual seminiferous tubules is occupied by a layer of spindleshaped cells that are particularly well developed in the ram and bear some resemblance to smooth muscle fibres (see Setchell, Scott, Voglmayr & Waites, 1969, for references). The seminiferous tubules are, therefore, capable of rhythmic contractions and these movements may facilitate the release of spermatozoa from the seminiferous epithelium and transport of spermatozoa out of the testis (see Setchell et al., 1969). Since oxytocin has been found to increase the frequency of contractions of seminiferous tubules in vitro (Niemi & Kormano, 1965), it might also be expected to influence the sperm output by the testis in vivo. Four Merino rams, aged 2 to 5 years and weighing between 46 and 60 kg, were kept in