[in Japanese]

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Modifications of extraction and separation of PGF_2α were made to improve recovery rate of PGFs (Figs. 1 & 2), and radioimmunoassay of their peripheral levels was tried in the cow and goat.
PGFs were extracted with ethyl acetate (5 ml, 10min. vibration × twice). The recovery rate of this procedure was 92.4% (Table 1). Separation was performed by using silicic acid column chroma-tography (φ, 10 mm). Changes in the recovery rate was examined for different column hights (3, 4, 5, and 6cm). But the results were not altered by the column hight used. The elution patterns of those chromatographies were essentially the same (Fig. 3). The overall recovery rate was approximately 90%.
Peripheral plasma levels of PGFs in the cow and goat during the estrous cycle were very low (50 pg/ml at most), and no significant fluctuation was detected.

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The relationships between the reproductive state and the adrenal structure of Sei Whales (Balae-noptera borealis) in the Antarctic Ocean were studied. 142 Sei Whales were examined. They were divided into three groups; immature, mature and pregnant. Judging of sexual maturity was based on body length, size of the ovary and the existence of corpus luteum. The adrenals were examined for weight and the ratio of cortex vs medulla (c/m ratio). Percentage of pregnancy was low (5%, 2/41) in smaller ones while the value increased up to 95% (39/41) in those larger than 14m in the body length, which suggests that adult body length of this species approximately 14m. It was found that adrenal weight was proportional to the body length and not affected pregnancy. These results suggested that pregnancy of Sei Whales in the Antarctic Ocean does not affect the weight and c/m ratio of the adrenal.

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Weak to strong activities each of Δ⁵3β-hydroxysteroid dehydrogenase (HSD) using dehydroepiand-rosterone, pregnenolone and 17α-hydroxypregnenolone as the substrates, of 17β-HSD using estradiol-17β and testosterone, of 20α-HSD using 20α-hydroxyprogesterone, and of 20β-HSD using 20β-hydroxyprogeste-rone, were demonstrated histochemically in the oocytes in antral follicles of 3 pigs (Yorkshire breed), 3 cattle (Holstein) and 3 horses (Thoroughbred), by the method of DICKMANN and DEY. Also demonstrated in such oocytes were moderate to strong activities of NADH₂-dehydrogenase (DH) and NADPH₂-DH both responsible for the reaction of HSD when the method of BARKA and ANDERSON was used.
The results above suggest that the oocytes in antral follicles of pigs, cattle and horses possess the ability to metabolize progestagens such as progesterone, 17α-hydroxyprogesterone, 20α-hydroxyproge-sterone and 20β-hydoroxyprogesterone as well as that to metabolize estrogens and androgens.

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The present study was undertaken to examine the production of monozygotic twins in goats by using two different methods. In method A, embryos were collected from superovulated donors 2.5 to 3.5 days after estrus and were separated into monozygotic twin embryos by using Willadsen's technique.⁷⁾This technique includes mechanical removal of zonae pellucidae, separation of blastomeres into two pairs, insertion into empty zonae, embedding in agar and culture for 3 to 5 days in ligated goat or rabbit oviducts. In method B, embryos were recovered 6.5 to 7.0 days after estrus and bisected by fine glass needle. This technique includes mechanical removal of zonae, bisection of embryos, insertion into empty zonae and culture in vitro for 16 to 20h. Results obtained are as follows.
1. Out of 39 embryos, 28 embryos (72%) were successfully separated into two by method A. Out of 48 half embryos transferred into goat oviducts, 20 (42%) were recovered and 8 (40%) had developed at the normal rate. Eight half embryos were transferred to 4 synchronized goats. Two of them were pregnant and each produced one kid. However, they were not monozygotic twins. Three out of 7 (43%) were recovered from rabbit oviducts and all of them developed normally. These 3 embryos were transferred to 2 synchronized recipients. One of them showed estrus on day 40 and the other on day 41.
2. Twenty out of 26 embryos were successfully bisected into two halves (78%) by method B. Twelve out of 40 halves (30%) were developed in vitro. These half embryos were transferred into 5 recipients, but all of them showed estrus at the expected day of the next cycle.

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The two-cell hamster embryos were transferred into the oviduct of pseudopreg-nant foster mothers through the infundibulum with a fine glass capillary pipette. Modified Krebs-Ringer's solution (280+Hepes) and tissue culture medium (TC-199) were used for the recovery and transfer of the embryos.
When two-cell embryos were transferred into the oviducts of foster females on Day-1 of pseudopregnancy, about 42% of the fosters became pregnant and about 10% of the transferred embryos developed into live young.
None of the females receiving embryos on Day-2 of pseudopregnancy became pregnant.

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The present experiment was aimed to improve the procedures for nonsurgical transfer of frozen-thawed embryos in cattle. Four morulas and one early blastocyst were collected nonsurgically from two donor heifers of Japanese Black breed at Days 7 of estrous cycle. The embryos were held at room temperature for 5 h before freezing in Whittingham's modified Dulbecco's PBS containing 20% bovine serum and appropriate antibiotics.
A straw of 0.25 ml capacity for freezing was filled with three compartments, each separated by small air bubbles. The middle compartment contained the embryo in PBS with 1 mole glycerol as cryoprotectant.
The upper and lower compartments contained 0.3 mole sucrose solution with 20% bovine serum.
After 27 days of preservation at -196 C, the contents were thawed at 37 C and mixed by shaking. Ten min later the embryos in the straw were transferred nonsurgically to five recipients two of which were diagnosed as pregnant by rectal palpation one at 40 and the other at 60 days later.

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Effects of high protein diet on the estrus cycle were investigated in 270 ICR-JCL mice. Animals were pair-fed for 28 days, using bovine milk casein as the base with high protein (70% casein; 3.62kcal/g) and control diets (24% casein; 3.61 kcal/g).
There was a significant correlation -0.974 between the lengths of pro-estrus and of di-estrus 2.
It was suggested that, with the prolongation of the days of pro-estrus, there was a shortening of di-estrus 2 phase.

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Histochemical caracteristics of lipids in the oocytes in antral follicles (3-10μm in dia-meter) of horses (Thoroughbred breed) were examined by following methods: the DADDI method(sudan III stain) for the demonstration of lipids in general, the CIACCIO method for lipoids, the SMITH method modified by KLEEBERG (nile blue sulfate stain) for neutral fats, the OKAMOTO, UEDA and KATO method for fatty acids, the SCHULTZ method for cholesterols, and the ALBERT and LEBLOND method for ketosteroids.
When the oocytes were stained with sudan III, their cytoplasm took a reddish orange color; treated by the CIACCIO method, a yellowish orange; and stained with nile blue sulfate, a pale red. They showed negative reactions when treated by the other three methods. These results suggest that the lipids in the horse oocytes are composed of lipoids and neutral fats.

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