Assessment of the ratio of live to dead spermatozoa showed that the ultimate loss of fertilizing capacity by the spermatozoa in both intact and gonadectomized males was not at first due to an increased incidence of dead spermatozoa in the epididymis, though progressively more dead and degenerated spermatozoa were gradually to be seen in the samples.The fertilizing capacity of the spermatozoa was lost more rapidly (within 8 days) in gonadectomized animals if they were also hypophysectomized. Administration of HCG to these animals failed to maintain normal viability in the spermatozoa.A gradual decrease in the occurrence of 'light' cells in the lining tissue of the duct is reported, following gonadectomy.It is concluded that circulating androgen is unquestionably required for the normal survival of spermatozoa in the tail of the hamster epididymis and that it probably achieves its effect through its influence on the epididymal epithelium. The findings are discussed in relation to the general hormonal control of sperm survival in the epididymis.

SUMMARY The effects of testosterone, dihydrotestosterone, 3α- and 3β-androstanediol on the fertilizing capacity of mature epididymal spermatozoa and on the production of fructose by the seminal vesicles were compared in golden hamsters. When injected subcutaneously into castrated animals, 100 μg testosterone, 75 μg dihydrotestosterone but only 12·5 μg 3α-androstanediol per day were required to maintain the fertilizing capacity at the control level for 12 days; 3β-androstanediol failed to maintain the fertilizing capacity of epididymal spermatozoa for 12 days. Although testosterone and dihydrotestosterone were equipotent in stimulating production of fructose by the seminal vesicles, 3α- and 3β-androstanediol were much less effective. The discrepancy in the response of the cauda epididymidis and seminal vesicles to 3α-androstanediol suggests that the hormonal requirements for sperm survival in the cauda epididymidis differ from those for the production of fructose in seminal vesicles. The results suggest that circulating testosterone may be relatively inactive in the cauda epididymidis and that the maintenance of fertilizing capacity of epididymal spermatozoa might be correlated with the reduction of dihydrotestosterone to the more potent androgen 3α-androstanediol by mature spermatozoa.

No abstract

SUMMARY The effect of progesterone on the maturation and viability of epididymal spermatozoa was tested in golden hamsters. The corpus epididymidis and ductus deferens were unilaterally ligated so that mature spermatozoa were isolated in the left cauda epididymidis whilst the contralateral epididymis was left intact. Fertility trials showed that after eight daily consecutive injections of progesterone (1·0 mg) spermatozoa on both sides retained normal fertilizing ability. Treatment with progesterone (0·25 and 1·0 mg) for 12 days, however, decreased the fertilization rate of retained spermatozoa to 44·4% and 0%, respectively, whereas fertilizing ability of spermatozoa from the intact cauda epididymidis remained unimpaired. In addition, progesterone (1·0 mg/day) did not influence passage of spermatozoa through the epididymis. Male hamsters treated with progesterone (0·25 mg/day) in combination with testosterone, 5α-dihydrotestosterone (5α-DHT) or 3α-androstanediol (all at 50 μg/day for 12 days revealed that 3α-androstanediol and 5α-DHT (but not testosterone) antagonized the antifertility effect of progesterone on retained epididymal spermatozoa. Furthermore, treatment of castrated hamsters with testosterone, 5α-DHT or 3α-androstanediol (100, 75 and 12·5 μg/day, respectively) in combination with progesterone (1·0 mg/day) showed that progesterone inhibited the stimulatory effect of testosterone but not that of 5α-DHT and 3α-androstanediol. The dissimilar effect of progesterone on fertilizing ability of spermatozoa in ligated and intact epididymides is discussed.

Fertile male hamsters were injected daily with 66 mg \g=a\-chlorohydrin/kg to determine the onset and duration of infertility. None of the males became infertile within the first 2 days but marked loss of fertilizing ability of spermatozoa had occurred by 24 hr from the second injection. Infertility occurred in all five males after the fourth dose. The fertilizing ability of the spermatozoa was not impaired when the equivalent of four daily doses was given as a single dose, thus indicating that sequential daily treatment was necessary for the induction of infertility. The prompt recovery of fertilizing ability of spermatozoa in males which had ligated ductuli efferentes and were given four daily doses of\g=a\-chlorohydrin (66 mg/kg) shows that transport of epididymal spermatozoa and their acquisition of fertilizing ability are not influenced by the drug.

Prostaglandins are present in the male accessory glands (Goldblatt, 1933; von Euler, 1935;Mann, 1964;Bygdeman, Fredericsson, Svanborg & Samuelsson, 1970), and can be synthesized by rat testis tissue (Ellis, 1972). Studies in sheep (McCracken, 1971;McCracken, Baird & Goding, 1971) indicate that prosta¬ glandins may be the naturally occurring luteolytic factor but the rôle of prostaglandins in male reproductive function has not been determined. Treatment of male rats and mice with prostaglandins E1; E2 and F2a however, decreases the level of circulating (plasma) testosterone (Bartke, Musto, Caldwell & Behrman, 1973;Saksena, El Safoury & Bartke, 1973). Since mature hamster spermatozoa lose their fertilizing ability within 12 days after castration (Lubicz-Nawrocki & Glover, 1973), it seemed possible that administration of prosta¬ glandins Et or 2 (PGEjl or PGF2t[) might induce sterility by lowering the titre of plasma testosterone. The present paper reports on the fertilizing ability of male hamsters treated with PGEj and PGF2a.Adult male golden hamsters (125 to 145 g) of known fertility were maintained under controlled conditions of temperature and lighting. Prostaglandins Et and F2a were dissolved in sterilized 0-9 % NaCl solution and refrigerated between injections. In order to test the effects of PGE! and PGF2a on the fertilizing ability of spermatozoa, six male hamsters were treated daily with 50 µg PGEX, and another group of six males received daily 50 µg PGF2a. Half of the daily dose was injected subcutaneously in 0-1 ml/100 g body weight at 08.30 hours and half at 20.30 hours. Three control animals were injected twice daily with 0-1 ml sterilized 0-9% NaCl solution. To test fertilizing ability, treated and control males were paired overnight with a female in oestrus; mating was confirmed by the presence of spermatozoa in the vagina and the females were killed approximately 40 hr after mating. Eggs were flushed from the uterine tubes with 0-2 ml Hanks' solution, mounted in toto (Chang, 1952) and examined with a phase contrast microscope for evidence of fertilization (the presence of a spermatozoon in the vitellus of a cleaved egg).For the estimation of plasma testosterone, treated and control males were anaesthetized with sodium pentobarbitone (Nembutal; Abbott Laboratories) the morning after mating, approximately 12 hr after the last injection of the prostaglandins. Blood was collected from the abdominal aorta into heparinized 557

Experiments with prepubertal hamsters were undertaken to determine if the appearance of spermatozoa with fertilizing capacity in the cauda epididymidis is related to age and/or body weight and whether the development of sperm function coincides with complete maturation of the mating behaviour pattern. At Week 6 after birth, intrauterine insemination of comparable numbers of spermatozoa showed that fertilizing capacity was related to body weight and not to age or seminal vesicular fructose concentration. In contrast to the low fertilization rate produced by spermatozoa from males weighing 80 g at Week 6 after birth, spermatozoa from 80-g males at Week 7 showed normal fertilizing capacity. Only 50% of 7-week-old males weighing 100\p=n-\110g produced fertile matings whereas all matings were fertile with males weighing 135 g and with males weighing 100 to 110 g that had received 7 consecutive daily injections of 50 \ g=m\ g testosterone beginning at Week 6 after birth. Comparison of sperm numbers in the cauda epididymidis and ductus deferens after mating at Week 7 showed that males which produced sterile matings were unable to terminate intromission with normal ejaculation of spermatozoa.

Summary. Mouse and hamster spermatozoa from the cauda epididymidis were deposited into the female tract at various periods following ligation of the corpus epididymidis. It was found that the number of spermatozoa in the cauda epididymidis decreased sooner in the hamster than in the mouse but the initial decrease in fertilizing ability occurred much earlier in the mouse than in the hamster. The fertilizing life of spermatozoa in the cauda epididymidis is approximately 25 days in both species.Spermatozoa develop their fertilizing ability during passage through the epididymis (Young, 1931;Bedford, 1966; Orgebin-Crist, 1967;Horan & Bedford, 1972) but gradually lose their ability to fertilize or to produce viable embryos after prolonged storage in the cauda epididymidis (Hammond & Asdell, 1926; Tesh 8c Glover, 1969;Lubicz-Nawrocki & Glover, 1973). Hammond & Asdell (1926) found that following bilateral ligation of the corpus epididymidis, most of the male rabbits became infertile after 38 days when the number of pregnancies and the size of litters were taken as criteria of fertility. Recently, Tesh & Glover (1969) reported that complete loss of fertilizing ability of rabbit spermatozoa occurs between 42 and 49 days after ligation of the corpus epididymis. The following experiments were designed to determine the fertilizing life of mouse and hamster spermatozoa and to ascertain the number of spermatozoa in the cauda epididymidis after its isolation from proximal regions by means of ligation.In order to age spermatozoa in the male tract, bilateral ligation of the corpus epididymidis was performed in mature CD-I mice (23 to 26 g) and golden hamsters (125 to 145 g). In male mice, the corpus epididymidis was exposed through a central abdominal incision. Two ligatures were placed between the caput and cauda epididymis and the intervening segment was removed. The testis and epididymis were manipulated back into the scrotum and testes were palpated at various times until the end of treatment to check that they remained in the scrotum. In hamsters, an incision was made in the scrotum and a single ligature was placed around the distal portion of the corpus epididymidis.In order to ascertain the number of spermatozoa in the cauda epididymidis after its isolation, the same number of male animals as used in the fertility tests (Table 1) were killed at the same post-operative intervals.165