This experiment was conducted to examine motility and fertility of goat spermatozoa which were frozen slowly in dry ice and alcohol and rapidly in liquid nitrogen vapor using ampoule and plastic straw. Semen was collected from 4 Sannen goats. The semen was diluted at the rate of 1 part of the semen to 4 of the first diluent ECSD (A) at 2527°C, which did not contain glycerol. The diluted semen was cooled to 4°C over a period of 1 hour and was kept for 23 hours at 4°C. The semen was rediluted at the rate of 1 part of the semen to 03 of the first diluent at 4°C. Then, the second diluent ECSD (B) containing 14% of glycerol (v/v) was added to the first or the rediluted semen at the rate of 1:1 four times at 15 minutes interval. The diluted semen was allowed to equilibrate at 4°C for 618 hours before freezing. Each 0.5 ml of the equilibrated semen was placed into the ampoule or plastic straw. One of the equilibrated semen samples was cooled gradually from 5°C to-15°C at 12°C per minute, -15°C to-30°C at 45°C per minute and -30°C to -75°C at 34°C per minute with dry ice and alcohol, then stored at-79°C. The other samples were cooled rapidly from 5°C to-100°C in liquid nitrogen vapor for 4 to 5 minutes and stored at-196°C in liquid nitrogen. The motility of spermatozoa before and after freezing was examined. The fertility of frozen spermatozoa was also tested. Insemination was performed by the deep cervical method with forceps and a pipette specially designed for goats and sheep. Volume of the semen was 0.5 ml per insemination, and the dilution rate was 10 to 30 times. The semen was thawed before insemination at 20°C.
The results obtained are as follows.
1. The optimum amount of egg yolk in the diluent was 20% (3% sodium citrate solution 4: egg yolk 1), and that of glycerol in the second diluent was 14 to 16%.
2. Effect of different glycerol equilibration time, 1.5 to 48 hours on motility of frozen sperma-tozoa was examined. The semen equilibrated for 6 to 18 hours gave good motility and high percentage of motile spermatozoa after thawing.
3. Good motility and high percentage of motile spermatozoa after thawing were obtained when a specially prepared diluent ECSD was used for goat semen. When ethylene glycol or propylene glycol was used instead of glycerol, the viability of spermatozoa decreased markdly.
4. Motility of spermatozoa was best when the semen was thawed at 30°C-40°C. However, in conception trials, satisfactory results were obtained with semen thawed at 20°C.
5. Effect of different dilution rates, 10 to 40 times, on motility of frozen spermatozoa was examined. Motility of spermatoza after thawing was generally good when it was diluted 10 to 20 times, but it was gradually decreased when it was diluted more than 20 times.
6. The dilution rate of the semen used for conception trials was 10 to 30 times. The frozen goat semen was stored at-79°C or-196°C for 1 to 1, 022 days. Each 0.5 ml of the semen was insemi-nated by deep-cervical method using forceps and a specially devised insemination pipette. All insemi-nations resulted in good conception rate, 71.9% for 114 goats with the semen from 15 male goats stored for 11, 022 days.
The longest record of storage of frozen goat semen with satisfactory conception was 1, 022 days. The conception rate from the field conception trials with the semen from 5 other male goats stored for not longer than 2 months was 81.8% (154/190) after single insemination.

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In the previous paper we found that most of the semen from boars agglutinated 10% egg yolk solution, sera from various kinds of animals and sometimes milk. This experiment was carried out to clarify some properties of these agglutinating factors in boar semen and some conditions, such as concentration of egg yolk, incubation temperature, pH value and concentration of various kinds of chlorides, which were influential to agglutinating activity.
Semen from boars was centrifuged, as soon as possible after collection at about 5°C and the seminal plasma was used immediately or stored at -20°C until required. Egg yolk diluent was prepared from the supernatant of egg yolk solved in distilled water. The pH value of diluent was adjusted by 1N-HC1 and 1N-NaOH. The agglutinating activity was expressed with an optical density at 550 mμ of a mixed solution of boar seminal plasma and egg yolk diluent measured by the electrophotometer.
The results obtained are as follows;
1. The agglutinating activity was affected by the concentration of egg yolk in the diluent added to seminal plasma. The optimal egg yolk level for agglutination was about 10%. Above 30% the agglutinating activity was inhibited.
2. The optimal mixing ratio of seminal plasma and egg yolk diluent, the agglutinating activity being expressed by the optical density, was 1:19.
3. Agglutination of egg yolk solution with boar seminal plasma was initiated immediately after dilution and reached the plateau about 60 minutes later. The optimal incubation temperature for agglutination was from 30° to 50°C.
4. The optimal pH value for agglutination was about 7 and the pH level in diluted seminal plasma changed little after incubation for 90 minutes at 30°C.
5. The agglutinating activity was almost inhibited in the presence of high concentration (10^-1 M) of various kinds of chlorides.

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This experiment was carried out to clarify some properties of protein precipitating factors in boar semen by agar gel diffusion method and to determine whether precipitation reaction was caused by immunoreaction or not.
The results obtained are as follows;
1. Boar seminal plasma having protein precipitating factors reacted sharply with 10% egg yolk solution and with autologus, homologus or heterologus serum, but not with the seminal plasma from other animal species, by Ouchterlony's agar gel diffusion method.
2. The precipitating factors were absorbed by washed bull and buck spermatozoa and also by bull spermatozoa heated at 100°C for 10 minutes. The red cells and these ghosts also absorbed the precipitating factors. The precipitating activity of boar seminal plasma did not disappear by heating at 70°C for 30 minutes, but the activity of pig serum antibodies was disappeared by heating at 70°C for 10 minutes.
3. The precipitation of boar seminal plasma to egg yolk solution was inhibited or tended to be inhibited in the presence of bull and buck seminai plasma, but not in the presence of that of cock, depending on the quantity of the plasma.
4. The serum from the boar precipitation positive semen did not develop precipitin line against egg yolk solution. The precipitating factors were not absorbed by antiserum to normal pig serum or by antiserum to pig IgG. The egg yolk solution or serum, heated at 100°C for 10 minutes, reacted with boar seminal plasma.
From the above results, it may be concluded that the precipitation of boar seminal plasma to egg yolk solution or serum is not due to the immunoreaction.

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Histological examinations of the follicular development and oocyte maturation division in ovaries were conducted in Wistar rats after administration of PGF_2α at the late stage of pregnancy.
Animals were kept under 12 hrs light/day (light on 06:00) in a 25°C room. In proestrus, female rats were caged with fertile males overnight and mating was checked by the presence of spermatozoa in the vaginal smear the following morning. This day was designated as day 1 of pregnancy. PGF_2α, 1000 μg/rat, was injected s. c. in 50% ethanol saline at 21:00 hr on day 19 of pregnancy (PG19 group) or at 09:00 hr on day 20 of pregnancy (PG20 group). In the PG19 group, the number of follicles over 550 μ in diameter increased to around 14 by 09:00 hr on day 20, with a striking contrast to a small number of these follicles in control pregnant animals. The total number of follicles over 300 μ and 550 μ in diameter at 10:00 hr on day 22 of pregnancy in the PG20 group was 55 and 14, respectively. The number of follicles over 300 μ did not change from the time of PGF_2α injection to the time of ovulation. The process of oocyte nucleus maturation division corresponded with that of the normal post-partum⁴⁾ and proestrous rats^{4, 12)}. Also, it was found that the timing of the begining of maturation division depended on the time of delivery rather than the time of PGF_2α injection.
These results may demonstrate that oocyte maturation division and ovulation during post-partum are closely related to the time of delivery.

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The transport of ova was studied in adult rats following treatment with varying doses (10 to 80i.u.) of human chorionic gonadotrophin (HCG). A total of 670 rats were killed 36 to 108 hours after HCG injection (or 24 to 96 hours after ovulation). The location of ova was examined in the four segments, I to IV, of the oviduct and in the uterus, as shown in figure 1.
The result obtained was as follows.
1. In untreated cycling rats, the relationship between the location of unfertilized ova and the time after ovulation was as follows: segments I and II at 24 hours; mostly in segments III and IV at 48 hours; some entering the uterus at 60 hours; mostly in the uterus at 84 hours; no ova present in the uterus at 96 hours. New ova derived from the subsequent ovulation were observed in the oviduct at 96 hours.
2 In HCG-treated rats, some ova were found in the uterus 48 to 60 hours after HCG injection (or 36 to 48 hours after ovulation) and about a half of the ova or most ova at 72 to 84 (or 60 to 72) hours. New ova originated from the subsequent ovulation were observed in the uterus of some rats 96 hours after HCG injection (or 84 hours after the preceding ovulation).
3. In untreated mated rats, fertilized ova were found in the following location at various time after ovulation: about a half of the ova in segment II at 24 hours; segments III and IV at 48 hours; most ova in segment IV at 60 to 66 hours; some ova in the uterus at 72 hours; most ova in the uterus at 78 to 84 hours; all the ova in the uterus at 96 hours.
4. When rats were treated with various doses of HCG and then mated with fertile males, most fertilized ova were found in segment IV of the oviduct and some ova in the uterus 60 to 72 hours after HCG injection (or 48 to 60 hours after ovulation). At 78 to 84 (66 to 72) hours, most ova were observed in the uterus. The percentage of rats with ova and the number of ova recovered from the uterus were reduced with the increase in the dose of HCG and with the lapse of time after HCG treatment.
5. From these findings, it seems that the ova are transported more rapidly in rats treated with various doses of HCG than in untreated rats. It is estimated that unfertilized and fertilized ova are transported 12 to 24 hours and 6 to 12 hours faster in treated rats than in untreated rats, respectively.

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The roles of androgen and FSH in the process of reduction division are still obscure. In this report, the effects of these hormones on reduction division were examined morphologically in rats hypophysectomized during the premeiotic phase.
Testicular weights were about three times heavier in rats injected simultaneously with FSH and TP than in those injected with either hormone alone. The weights of the accessory reproductive organs, including the epididymis and the prostate gland, of the former rats were also heavier than those of the latter. Development of seminiferous tubules was accelerated remarkably in the former rats.
The number of type B spermatogonia increased in the rats injected with FSH and TP, and that of preleptotene spermatocytes in rats injected with ICSH or FSH alone, or with FSH and TP simul-taneously. The maturation from preleptotene to pachytene spermatocytes was more remarkable in a rat injected with FSH and TP than in any other rat. The ratio of pachytene spermatocytes to spermatids was the highest in rats injected with TP alone. The number of spermatids in the tubular cross-section was the largest in rats injected with FSH and TP, which were followed by rats injected with ICSH or TP alone. In rats injected with FSH alone, it was just a few. Spermatids were allowed to progress into step 13 of the acrosomic phase of spermiogenesis in rats injected with FSH and TP. They remained, however, in the cap phase in any other rat. The ratio of seminiferous tubules containing spermatids to whole tubules in a testicular cross-section was the highest in rats injected with FSH and TP.
From these results, it was considered that the process of reduction division might be controlled mainly by androgen, and that the maturation of young spermatids might be accelerated by the synergistic action of FSH and TP.

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An experiment was conducted to determine whether the administration of prostaglandin F_2α (PGF_2α) affects the pattern of uterine contractions at 8, 16 and 24 hours after the detection of estrus.
Uterine contractions were observed by laparotomy under intravenous anaesthesia with 8 to 10 ml of pentobalbital-Na. According to the method of CROKER and SHELTON (1973), individual contractions were classified as moving towards the body of the uterus, moving towards the oviducts, or in neither direction (i.e. stationary). There was no significant difference between the treated and the control groups in the total number of contractions and in the three classification of contractions. The proportions of total contractions moving towards the oviducts, not moving clearly in either direction, or moving towards the cervix, were 51.1%, 25.5% and 23.4% in the PGF2c, group, and 49.8%, 32.5% and 17.7% in the control group.
PGF_2α treatment did not decrease the number of contractions moving towards the oviducts and resulted in a similar pattern of uterine contractions to that in the control group.

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It is very suspicious that a lack of libido, asthenospermia and azoospermia of boars which have occurred from summer to autumn must be caused by an infection of Japanese encephalitis virus (JEV). The present study was conducted to prove the suspicion by using the boar infected experi-mentally with JEV.
The virus used was the AS-6 strain which had been isolated from the blood of swine involved in an epizootic outbreak of Japanese encephalitis in the field, and which had undergone three pas-sages in the suckling mouse brain. Five boars 78 months old which had been ascertained to be negative for antibody against JEV were inoculated subcutaneously with 1 ml of viral material of 10^6.510^9.0 TCID₅₀/ml.
Viremia occurred 23 days after the inoculation. Body temperature increased to 39.541.2°C, which lasted for 0.55 days in all the boars. JEV was recovered from the semen in 2 boars over a period from the next to the 17th day, and from the 3rd and the 17th day after inoculation, re-spectively. In boars in which a relatively high temperature continued, libido decreased and no semen collection was possible. When body temperature recovered to the normal level, the motility and concentration of sperms were reduced in 2 boars, but in the other 3 boars only sperm motility was reduced slightly. A high incidence of abnormal sperms was observed in one boar.
All the boars were subjected to autopsy over a period from 23 to 146 days after inoculation. Yellow fibrin was deposited on the surface of the tunica vaginalis communis and the tunica testis of spermatic cord and testes in all of them, and hydrocele in the scrotal cavity presented in two of them. In both parietal and visceral tunica and interstices of the epididymides, inflammatory changes of various degrees were observed. The disturbance of spermatogenesis was found in some seminifer-ous tubules.
These results indicate that reproductive disorders must have occurred to the boar in association with the infection of JEV.

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