Two female chimpanzees were inseminated artificially using semen obtained by electro-ejaculation from a male. Optimal day for insemination was estimated by monitoring sex skin swelling, and by serum and urinary LH concentrations. Insemination was repeated 2 to 4 times every other day intra-cervical or intravaginal, deposition was chosen according to the condition of semen. To confirm pregnancy, the levels of urinary chorionic gonadotropin were measured daily after insemination. By cesarean section, one female baby was delivered on day 219 after the first day of insemination and the other of the same sex on day 211, weighing 1, 760g and 1, 480g respectively.

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Progesterone (P) levels in skim milk from 38 postpartum Holstein Friesian cows were determined by a direct enzyme immunoassay. The cows were reared in commercial dairy farms in northern Hokkaido.
Milk samples for assay were prepared from whole milk obtained from any one of four udder quarters at morning milking. Samples were collected 3 times a week; Monday, Wednesday and Friday, from 1st to 10th week postpartum. The ovaries were examined by weekly rectal palpation.
Results are summarized as follows:
1. Chronological changes in the milk P levels in these cows may be classified into 4 types. Type I (normal): cyclic changes in milk P levels appears before 20 days postpartum (7 cows, 18.4%). Type II (delayed elevation of P level): cyclic changes of milk P levels did not occur before 20 days post-partum (21 cows, 55.3%). Type III: after a transient rise of milk P level the levels remained low (9 cows, 23.7%). Type IV: after the second peak a high P level was maintained (1 cow, 2.6%) (see Fig. 1.).
2. Of the cows classified as type II, 11 had inactive ovaries and remaining 10 had follicular cysts.
3. Of the cows classified as type III, 5 had inactive ovaries and 4 had follicular cysts.
4. The cows of type IV was diagnosed as bearing persistent corpus leteum.
These results indicate that P levels in milk assessed by enzyme immunoassay can be utilized for monitoring postpartum ovarian activity and would be helpful for the early detection of ovarian dys-function in the milking cow.

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Seventeen dairy Holstein cows diagnosed as bearing postpartum inactive ovaries by repeated rectal palpations were divided into 4 groups. Three cows each of Groups I and II and 5 cows of Group III were treated by a single intramuscular injection with 200μg of LH-RH analogue ([Des-Gly-NH₂¹⁰, Pro-ethylamide⁹]-LH-RH; LH-RH-A) on Day 7, on Day 13-14 and on Day 21-22 (Day 0 being the day of parturition), respectively. Six cows of Group IV were served as untreated controls. Changes in the ovary after treatment were examined by rectal palpation at intervals of one or two days. Plasma progesterone concentrations were determined by radioimmunoassay in blood samples collected by jugular vein puncture every two days.
Following results were obtained.
1. Ovulation was induced over a period from 24 to 48h after LH-RH-A treatment in 2 cows each of Groups I and II and 4 cows of Group III; i.e. eight (72.7%) of the 11 cows in total. Ovarian func-tion became active in these 8 cows after induced ovulation.
2. The responsiveness of the ovary to LH-RH-A treatment was better on Day 21 than on Day 14 or 7, judging from the results of induced ovulation that was followed by ovarian activation.
3. A normal ovarian cycle recurred by at least two processes after induced ovulation. 1); The corpus luteum (CL), formed after induced ovulation, was subnormal in size and began to degenerate as early as 7 days after ovulation. A follicle became palpable about 2 days after ovulation grew up and ovulated about 10 days after induced ovulation. During this time span, progesterone increased slight by 2ng/ml even at the peak. 2); The CL was normal in general and began to degenerate about 15 days after induced ovulation. So, a follicle became palpable about 11 days after ovulation ovulated about 20 days after induced ovulation. Progesterone increased after induced ovulation and remained at a high level for about 15 days. The same two processes were also recognized after 1st ovulation in the 6 untreated controls.
4. Estrous signs were generally obscure at the time of the 1st ovulation induced by LH-RH-A or occurred spontaneously, but they became obvious in most cases at the 2nd and 3rd ovulation after parturition.
These results indicated that a single intramuscular injection with 200μg of LH-RH-A was effec-tive enough to induce an ovarian cyclic activity in postpartum dairy cows in which the ovaries were still inactive on Day 21 after parturition.

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Plasma estradiol-17β (E₂) and progesterone (P) levels were studied about jugular blood samples collected either every day in follicular phase or every other day in luteal phase from 3 postpartum cows (2 Holsteins and a Japanese black) and a Holstein cow in which cesarean section was performed on the 4-5th month of pregnancy. At the same time, ovarian activities were examined daily by rectal palpation and estrous signs were checked twice daily during follicular phase.
Until postpartum first ovulation, which occurred at 14-40 days postpartum, plasma P levels did not exceed 0.4ng/ml. E₂ levels during this period were rather low, but showed a little increase before first ovulation. The first ovulation was not preceded by estrous signs.
The length of first estrous cycle in the 3 postpartum cows was shorter (9-14 days) than that observed in the ordinary cycle length. Corpora lutea in this stage seemed to be subfunctional and plasma P levels never exceeded 1.0ng/m_l.
On the contrary, the cow No. 4 in which cesarean section was performed showed high plasma E₂ and P levels till first ovulation after the operation. These high levels may be originated from re-tained placenta and corpus luteum of pregnancy. The first ovulation was preceded by marked estrous signs in this cow. The corpus luteum in the first estrous cycle (17 days) was also very functional and the patterns of plasma E₂ and P levels were quite similar to those of cycles after second ovulation with normal ovarian activities in the cow No. 2 and No. 3. It was suggested that the ovarian func-tion of this animal had already recovered at this stage.
After second ovulation, nearly normal ovarian activities were confirmed by palpation in 2 (No. 2 and No. 3) of the 3 postpartum cows. In the 2 cows, although some of the subsequent ovulations were preceded by estrous signs, the remaining cows were silent. In these animals, plasma E₂ levels in-creased after ovulation, showed a little peak in luteal phase, then decreased, increased again in follicular phase and showed a peak (4.3-16.7pg/ml) 1-3 days before ovulation. P levels increased after ovulation, showed a peak (2.5-8.0ng/ml) in luteal phase, decreased suddenly at 5-8 days before next ovulation and the low levels were maintained at the time of ovulation.
In the cycle of cow No. 1, cystic corpus luteum (CCL) developed and ruptured during palpation 9 days after ovulation. The follicle in the ipsilateral ovary developed rapidly after the CCL rupture and became cystic, and the cystic follicle existed about 60 days thereafter. During the CCL forma-tion, plasma P levels were below 0.8ng/ml, but after the rupture, they elevated along with luteiniza-tion of CCL and showed a peak of 6.1ng/ml. E₂ levels increased rapidly during the cystic follicle formation and elevated to a peak level (12.9pg/ml) 3 days after the CCL rupture and suddenly de-creased thereafter. In the second and third cycles of this animal having a cystic follicle, plasma E₂levels were low.
Plasma E₂ and P levels in 6 estrous cycles with normal estrus were compared to those in 6 cycles with silent estrus. Plasma P levels in the luteal phase in the cycles with silent estrus tended to form the peak earlier and declined more solwly than in the cycles with normal estrus.

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Histochemically detection of the activities of cytochrome oxidase, NADH₂ dehydrogenase (NADH₂-DH), lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), α-glycerophosphase de-hydrogenase (α-GPDH) and Δ⁵-3β -hydroxysteroid dehydrogenase (Δ⁵-3β-HSD) were carried out in intact mouse blastocysts on Day 4 and in delayed implanting mouse blastocysts during the period from Days 10 to 30.
The activity of cytochrome oxidase was demonstrated by the BURSTONE method, those of NADH₂-DH, LDH and a-GPDH by the BARKA and ANDERSON methods, that of SDH by the method of NACHLAS et al. and that of Δ⁵-3β-HSD by the DICKMANN and DEY method. In the blastocysts treated by the method for the demonstration of cytochrome oxidase, pyrazolone granules were deposited in the cytoplasm of both cells of trophoblast inner-cell-mass, but in those treated by the methods for dehydrogenase, diformazan granules were deposited in the cytoplasm of the respective cells.
In intact blastocysts, the activities of cytochrome oxidase, LDH and Δ⁵-3β-HSD were strong, while those of NADH₂-DH, SDH and α-GPDH ware weak. In delayed implanting blastocysts, the section of cytochrome oxidase was strong, while that of NADH₂-DH and SDH was weak throughout the period of delay just as seen in intact blastocysts. Throughout the delayed period, a weak activity of α-GPDH was seen in the trophoblasts, but none in the inner cell mass. In most of the delayed implanting blastocysts, the activity of LDH was strong, but it was weak in some blastocysts on Days 17, 24 and 30. The activity of Δ⁵-3β-HSD was weak throughout the delayed period.

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The purpose of this study is to investigate the secretion pattern of PGFs originated from the uterus and its correlation with progesterone (P) secretion in Japanese native Shiba-goats.
PGFs levels in the plasma samples collected from uterine branch of ovarian vein via silicon catheter which had been inserted into the inosculation point of uterine and ovarian branches of the ovarian vein, and P levels in the peripheral plasma samples were determined by RIA. Four female Shiba-goats were used in the present experiment (Table 1).
As shown in Figs. 1-3, PGFs levels in 3 animals with normal estrous cycle began to increase around Day 12 and formed the peak (3.5ng/ml, 14.5ng/ml, 3.3ng/ml) on Day 16-17. Thereafter, PGFs levels decreased and returned to the basal level 24h before the expected next estrus.
On the other hand, P levels began to decrease around Day 14 and showed rapid decrease on Day 15. The lowest levels were seen on Day 17-18 (Figs. 2 & 3).
In one animal in which no corpus luteum was confirmed at the time of catheterization, both PGFs and P levels were maintained low (Fig. 4).
From these results, it was concluded that the increase in the PGFs levels in uterine branch of the ovarian vein preceded the luteolysis in Shiba-goats as known in many other domestic and experi-mental animals.

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The present study was undertaken to find out the suitable methods for blastomere fusion of mouse 2-cell embryos using polyethylene glycol (PEG). Two-cell embryos were treated with 4 kinds of PEG products at varying concentrations for varying length of time, and those that showed blasmatomere fusion were cultured for 3 days to observe their development. The results obtained are as follows.
1) Incidence of blastomere fusion was not significantly different among the embryos with zonae pellucidae were left intact, partially cut open, and completely removed.
2) The proportion of the embryos that developed to blastocysts after blastomere fusion was in-fluenced by PEG products. PEG of Sigma and Wako (molecular weights 1, 000) were superior to others. PEG of Merk was completely ineffective for blastomere fusion.
3) The high proportion of blastomere fusion and development to blastocysts were obtained when the embryos were treated with 45% PEG for 90 to 120 seconds or 50% PEG for 90 seconds.
4) The addition of DMSO to PEG was not effective for enhancement of blastomere fusion.

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Binding of hexestrol dicaprylate (H₈) on the estrogen receptor in the canine prostate was investi-gated. Six male dogs were injected with a single dose of 20mg/kg of H₈ 25 days after castration. On the 28th day after H₈ injection, the prostate was removed. In the dogs treated with H₈, the size of the prostate gland exceeded that of the castrated control dogs by 3 times, and the epithelial proli-feration with stratified squamous metaplasia and the dilated acinar lumina filled with keratinized epithelial detritus were found histologically.
Canine prostate cytosol was incubated with either H₈ or hexestrol (H₀) and [³H]-estradiol ([³]-E₂) at 4C for 18h. Following incubation, [³H]-E₂ binding to the estrogen receptor was separated from free [³H]-E₂ using dextran coated charcoal. H₀ strongly competed with [³H]-E₂ for binding to the estrogen receptor, while H₈ weakly competed with [³H]-E₂. Prostate cytosol was also incubated with either H₈ or H₀ and [³H]-R1881 (the synthetic androgen) at 4C for 24h. Neither H₈ nor H₀ competed with [³H]-R1881 for binding to the androgen receptor.
These results indicated that H₈ after being hydrolyzed to H₀ bound to the estrogen receptor in the prostate gland and caused the enlargement of the gland.

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Effects of synthetic gonadotropin releasing hormone (GnRH) and rabbit anti-pregnant mare serum gonadotropin (PMSG) on numbers of ovulation, fertility and prolificacy were investigated in 59 Suffolk ewes in which estrus was induced by a progestin (methyl-acetoxyprogesterone: MAP)-impregnated vaginal sponge and 750IU PMSG during anestrous season. The animals, at the time of estrus, were administered intramuscularly either with saline (group I), 150μg GnRH (group II), or rabbit anti-PMSG serum that could neutralize the potency of 750IU PMSG (group III) and artificially inseminated. A total of 56 ewes (group I: 18, group II: 19 and group III: 19) were inseminated with fresh-undiluted semen.. Although pregnancy rates were not significantly different among these groups, lambing rate in group II (57.9%) was significantly higher than group I (16.7%: P<0.01) and Group III (26.3%: P<0.05). Prolificacy were not significantly different among the groups (1.67±0.58, 1.19±0.83 and 2.20± 0.84 for groups I, II and III, respectively). Numbers of ovulations and follicles of >5 mm in diameter, examined at the 8th day after PMSG treatment in 10 ewes per group, were also not significantly different among the groups. However, wastage proportion of eggs or embroys significantly (P<0.025) decreased in GnRH-injected ewes (64.3%) as compared with that in saline-treated ewes (90.0%). A decrease in the plasma concentration of estradiol-17β, caused by anti-PMSG treatment did not improve the fertility. These results indicate that a single intramuscular injection of GnRH at the onset of estrus, induced with MAP sponge and PMSG treatments, was effective for improvement of fertility in ewes during non-breeding season.

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Progesterone releasing intravaginal device (PRID) with or without the estra-diol benzoate (E.B.) capsule was used for synchronization of estrus and improvement of the subsequent fertility in Japanese Black cattle. PRID was inserted into the vagina for 12 days in 12 animals; consisting of 8 without the E.B. capsule (group I) and 4 with the capsule (group II). They were administered a single intramuscular injection of 25 mg prostaglandin F₂α (PGF₂α) 24 h before PRID removal. Six animals received two injections of 25 mg PGF₂α 11 days apart (group III) and 7 animals served as control (group IV). All animals were cyclic, but have not conceived by 1-3 services including artificial insemination. Estrus was examined continuously for 5 days after treatment and estrous animals were artificially in-seminated once with frozen-thawed bull semen. Serum progesterone (P) levels on day 20-21 (>2.0 ng/ml), non-return (N.R.) and the rectal palpation (R.P.) 60-90 days after insemination were examined for fertility. A retention rate of PRID for the period of 12 days insertion was 75.0% (9/12). All animals except one in group II showed estrus within 5 days after treat-ment. Mean intervals between the cessation of treatment and the onset of first "standing" estrus were 66±28, 51±14 and 52±9h for groups I, II and III, respectively. The incidence of estrus delayed in animals which lost the PRID and were re-inserted a new PRID during the treatment period. Fertility rates in groups I, II, III and IV were 87.5, 25.0, 82.5 and 80.0% by P level, 62.5, 50.0, 50.0 and 57.2% by N.R. and 62.5, 25.0, 50.0 and 57.2% by R.P., respectively. The results indicate that a combined treatment of a PRID and PGF₂α was effective for synchronizing estrus and permitting satisfactory fertility following treatment in Japanese Black heifers and cows which had not conceived.

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