The male rabbit. V. Changes in sperm reserves and resorption rate induced by ejaculation and sexual rest.

T HE maximum number of sperm which can be obtained by ejaculating domestic mammals apparently is less than the number produced by the testes (Amann and Almquist, 1962a, b; Kennelly and Foote, 1964; OrgebinCrist, 1968). The fate of unejaculated sperm is uncertain. Koefoed-Johnsen (1964) and Lino et al. (1967) showed that bulls and rams eliminate some sperm through micturition or masturbation. However, the number of sperm voided in the urine may be a small percentage of the production. Simeone and Young ( 1931 ), Kennelly (1960) and KoefoedJohnsen (1964) concluded that most unejaculated sperm are resorbed in the excurrent duct system. Amann and Almquist (1962a) postulated that the rate of sperm resorption was variable and increased as the number of sperm in the cauda epididymidis increased. For rabbits, 64% of the sperm stored in the caudae epididymides and ductuli deferentia were collected in four successive ejaculates (Kirton et al., 1967). I f the above postulate of Amann and Almquist (1962a) is correct, the rate of sperm resorption should be minimal after such a drastic reduction of the number of sperm in the caudae epididymides. Similarly, if the rate of resorption increases as the number of sperm in the caudae is restored, the net rate of refilling ultimately should_ decrease and differ markedly from the rate of sperm production. The objectives of these studies with rabbits were to determine: (a) the influence of ejaculation on sperm reserves and (b) if the rate of sperm accumulation in the epididymis is variable after collection of 10 successive ejaculates.