Histochemical examinations of proteins, neutral and acid polysaccharides, and lipids were made using the oocytes in primordial, secondary and antral follicles and the embryos at the stages of 1- to 8-cell, morula and blastocyst of the mastomys, Praomys natalensis. The cytoplasm and zona pellucida of both oocytes and embryos always contained acrolein-Schiff reactive proteins, but not sudanophilic lipids. The zona pellucida of both oocytes and embryos contained neutral polysaccharides that were periodic acid-Schiff reactive and salivary test-resistant, and alcian blue positive acid polysaccharides, while the cytoplasm of those possessed no such substances. The cytoplasm of oocytes in secondary and antral follicles and of embryos at the stages of 1-cell to blastocyst possessed a large amount of glycogen granules that were periodic acid-Schiff reactive and salivary test-digestible.

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Triploid embryos were produced from degynic ICR eggs fertilized with ICR or C57BL/6J spermatozoa in the presence of 5 μg/ml cytochalasin B in vitro. About 60% of these tripronuclear eggs developed into the blastocyst when cultured in a modified Whitten medium supplemented with 100 μM EDTA. At the eight-cell stage, each of the triploid embryos was aggregated with a normal diploid ICR or F₁ (ICR × C57BL) embryo after removing their zona pellucida with pronase. The rate of development to a single blastocyst was 94.0% and 89.5% in the aggregated pairs of 2n (ICR egg × C57BL sperm)↔3n (ICR egg × ICR sperm), and 2n (ICR egg × ICR sperm)↔3n (ICR egg × C57BL sperm), respectively. Karyotyping has revealed that these chimeric blastocysts are composed of both 2n and 3n cells.

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The aggregated diploid↔digynic triploid chimeric embryos were transferred into the uteri of ICR pseudopregnant females. Of the 99 2n (ICR × C57BL/6J)↔3n(ICR × ICR) and 163 2n (ICR × ICR)↔3n(ICR × C57BL/6J) chimeric embryos transferred, 47 (47.5%) and 56 (34.4%) developed to term. Percentages of mice with chimeric coat color were 26.2% (11/42) and 27.7% (13/47) in the offspring derived from the 2n (F₁)↔3n (ICR) and 2n (ICR)↔3n (F₁) chimeric embryos, respectively. Very small number (<1%) of 3n metaphase plates were observed in the preparations of bone marrow cells from the 2n↔3n chimeras, while 1.4-15.6% of the cultured tail cells showed 3n chromosomes in these animals. All of the 5 females and 4 of 5 males of the 2n (ICR)↔3n (F₁) chimeras were proved to be fertile after mating with ICR mice, and produced a total of 147 albino progeny showing that all of them were derived from the diploid cell lines.

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Relationships among 16 behavioral variants of virgin, pregnant and lactating female mice were investigated by factor analysis. In total, 28 mice from C3H/He, C57BL/6, DBA/2 and DDD inbred strains were used. The variants analyzed were 3 from open-field activities, 4 from nest-buildings, 7 from spontaneous behaviors, and 2 from synthetics.
Eighty percent of the cumulative eugen-value could be classified into 6 factors. Factor 1 seemed to be related to the complex locomotion; Factor 2 to the specific spontaneous behaviors at pregnant stage; Factor 3 to the simple locomotion, and Factor 4 to the emotionality. The results obtained suggest that the behavior of collecting and manufacturing of the nest-material as well as the locomotion behavior of inside and outside areas of the open-field, was controlled by different mechanisms. The characteristic feature to be adsorbed in a single behavior seemed to correlate with the low milk yield in the mouse.

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Changes in serum inhibin concentrations during the menstrual cycle were studied in 6 Japanese monkeys (Macaca fuscata fuscata) by a heterologous radioimmunoassay (RIA) based on a bovine RIA. Serum levels of estradiol-17β, progesterone, LH and FSH were also monitored. Inhibin levels in the serum were low during the early and midfollicular phases, followed by a slight increase during the late follicular phase. A marked increase in serum inhibin was found during the luteal phase. Changes in serum inhibin during the luteal phase were positively correlated with those in serum progesterone, whereas serum FSH remained suppressed during the luteal phase. These results suggest that both the corpora lutea and the antral follicles are the sources of circulating inhibin in the female Japanese monkey.

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A total of 226 first lactating Holstein cows were treated with commercially available porcine FSH (FSH-P) and PGF_2α(Tham-salt) or PGF_2α, -analogue (cloprostenol) at the mid-functional luteal stage to induce twin pregnancy. The rate of showing estrus was lower in cows treated with PGF_2α 1520 mg than PGF_2α, -analogue 0.5 mg, and there was not difference between PGF_2α, -analogue 0.5 mg and PGF_2α 30 mg. The 24-hrs interval between the first FSH-P and PGF_2α-analogue injection was slightly more effective than the 48-hrs interval to induce estrus and pregnancy. Total amount of FSH-P was positively correlated with the number of corpora lutea (CL) after estrus, and 1215 AU FSH-P treatment induced higher percentages of cows with 3 CL or over and abortion than those of 6-10 AU FSH-P treatment. No difference was noted in response to a total 6 AU FSH-P treatment between 1 and 2 injections per day through 2 days. The rate of abortion in the pregnant cows with 1, 2 and 3 CL were 1/20, 1/23 and 4/14, respectively. Therefore, it is suggested the appropriate ovulation rate is 2 and that treatment with 46 AU FSH-P on the first day and 24 AU FSH-P plus 0.5 mg PGF_2α, -analogue on the second day is the practical schedule of the hormonal treatment.

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Primers, whose base sequence was homologous to the 1-20 and 541-560 by of bovine Y chromosome-specific DNA probe ES8 (630 bp) (Ellis et al., 1988), were prepared. Using these primers, male and female bovine genomic DNA was amplified by PCR. Four unknown DNA fragments were detected in amplified male DNA alone. These fragments were also detected by PCR using 10^-6 μg of male DNA.
When the base sequences of these DNA fragments were determined by the dideoxy method, none of them matched the base sequence of ES8. When their base sequences were examined for partial matching with the base sequence of ES8, the percentage of agreement was 65% in the case of the 92 by fragment (I0-1), 51% for the 142 bp fragment (I0-2), 57% for the 170 bp fragment (I0-3) and 84% for the 224 bp fragment (I0-4). Hybridization of these sequence-determined DNA fragments to male and female bovine DNA demonstrated the male specificity of these fragments. These results suggest that the 4 DNA fragments obtained in the present study can be utilized as bovine male-specific DNA fragments.

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Prostaglandin (PG) E₂ at the final concentrations between 2010000 ng/ml, stimulated progesterone (P₄) output from the porcine corpus luteal cells in culture. It is suggested that PGE₂ has a luteotropic effect to porcine corpus lutea in vivo. PGF_2α did not have any clear effect on P₄ output from luteal cells. On the contrary, oxytocin and platelet activating factor have the suppressive effect on P₄ output from luteal cells in culture. These results mean that they have luteolytic effect to porcine corpus lutea.

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Effects of gonadotropins (10 μg/ml LH and 2 or 10 μg/ml FSH) and estradiol-17β (E₂:2 μg/ml) added into a maturation medium of bovine oocytes were evaluated for the subsequent capacity of in vitro fertilization and embryonic development into blastocysts after culturing in therabbit oviducts. Immature bovine oocytes collected from follicles of 25 mm in diameter and enclosed with cumulus cells were cultured in vitro for 22 hr in TCM-199 medium containing 25 mM HEPES, 10%(V/V)fetal calf serum, antibiotics and hormones. The combinations of the hormones added to the medium were as follows; (A) none, (B) LH+E₂, (C) FSH (2 μg/ml/)+LH+E₂, and (D) FSH(10 μg/ml)+LH+E₂. The fertilization rates and the developmental rates of 4-cell embryos into blastocysts were not significantly affected by the addition of hormones. The fertilization rates and the developmental rates into blastocysts were: 90.9%(40/44) and 39.6%(40/101) for group A, and 90.7%(39/43) and 34.7%(26/75) for group D. The present study indicates that the addition of hormones to a maturation medium has no positive effect on the capacity for fertilization and embryonic development of bovine oocytes matured in vitro.

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The filtrate of bacteria-culturing medium was infused into the uterus of cows having subfunctional ovaries. The bacteria were isolated from the uterine cervix of a cow. As a result, follicular development, estrus-like behavior and cervical mucus secretion were induced, suggesting the elevation of estrogen levels. Though the ovarian volume increased, the follicles did not fully develop as ones during an estrus stage and were soft and irregularly shaped. Ovulation and corpus luteum formation were not observed. The ovary may have capacity to respond to bacterial infection in the uterus with an increase in estrogen secretion.

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The rate and latency of the occurrence of estrus were compared between the PGF_2α treatments of intramuscular injection and intrauterine infusion to cows for embryo tranfer. PGF_2α (each 10 mg) was injected daily intramuscularly 3 times to 17 donors and twice to 50 recipients. And to 16 donors and 55 recipients, PGF_2α(5 mg) was infused into the ipsilateral uterine horn to the ovary bearing the functional corpus luteum using an instrument with a concentric sheath. PGF_2α treatments were done 48 hr after the 1st FSH injection. Standing estrus was observed in donors 40 to 48 hr after the PGF_2α treatment in 93.8% cows by the intrauterine infusion and 88.2% cows by the intramuscular injection. As for the recipients, standing estrus was induced mainly between 40 to 96 hr after the intrauterine infusion or 40 to 144 hr after the intramuscular injection. If the observational period was limited between 40 to 72 hr, estrus was induced in 87.3% cows by the former treatment or 46.0% cows by the latter treatment. The former was significantly higher (P<0.05).
For the synchronization of the occurrence of estrus in cows, the intrauterine treatment with PGF_2α using an infusion instrument can be recommended.

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