The twenty mares of heavy breed, those were maiden or barren in the previous breeding season, were bred by running mares with a stallion during two months from the late March to May, 1971.
The results obtained were as follows:
1. All mares showed signs of oestrus and eleven of them were conceived. It is suggested that nine mares out of eleven were conceived during the first half of the period. Some defects of ovaries, uteri and/or vaginae were found in seven out of nine infertile mares.
2. It was observed that the mating in the daytime was less frequent and only nine matings of eight mares took place in the daytime. Judging from the results, it seems that the mating may be took place at night or early in the morning.
3. In three cases, the mating took place much earlier than the day of ovulation. However, the observations are insufficient to ascertain whether this phenomenon will occur usually or not.
4. It was often observed that a mare seems to disturb the contact of the oestrous mare to the stallion.
5. Although the stallion seemed to be exhausted during a few days in the beginnig of this trial, he recovered himself thereafter. With regard to the mares, no injuries were recognized.

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The effect of gonadotrophin treatment on implantation and blastula stage of ova in adult rats was studied. A total of 590 rats were kept under artificial lighting conditions (night controlled for 10 hours from 1 a. m. to 11 a. m.) and injected with human chorionic gonadotrophin (HCG) 12 hours before the time of estimated ovulation (9 p. m. or 4 hours before the beginning of night), together with or without a priming of mare serum gonadatrophin (PMS) performed 54 hours before HCGtreatment (3 p. m.). Then they were allowed to copulate at the time of estimated ovulation (9 a. m.). Experiments were carried out to examine the effect of storage of dissolved-hormones by means of induced ovulation and superovulation. In them, 90 adult rats were treated with HCG 36 hours before the time of estimated ovulation, and 175 immature rats with PMS alone or PMS and HCG at an interval of 54 hours. Then all the rats were killed 20 hours later.
The results obtained are as follows. 1) When three groups of rats were treated with 25 I. U. of HCG, 50 I. U. of HCG, no hormone (control), respectively, and killed 9 days after copulation, the percentage of rats with implantation sites was 4.2% (4 out of 95 rats), 0% (0/60), and 90.6% (58/64), respectively.
2) When six groups of rats were treated with 5 I. U., 10 I. U., 25 I. U. and 50 I. U. of HCG, 20 I. U. of PMS plus 10 I. U. of HCG, and no hormones, respectively, and examined at autopsy 96 to 97 hours after copulation, the percentage of rats with ova of blastula stage was 66.7% (18 out of 27 rats), 25.6 % (20/78), 3.3% (2/61), 0% (0/50), 15.1 % (8/53), and 100% (30/30), respectively.
3) From the results metioned above it seems that the treatment of gonadotrophins may have an injurious effect on ova of blastula stage and implantation in adult rats. It is also suggested that the results of the previous experiment on implantation (ISHIBASHI et al., 1970) may be regarded as data obtained under the condition of decreasing hormonal efficiecy, because of the experimental errors included in them. At present, however, it is difficult to examine whether this suggestion is true or not.
4) When three groups of rats were treated with 25 I. U. of HCG (in such dissolution as containing 100 I. U. per ml), 25 I. U. (50 I. U./ml), and 10 I. U. (50 I. U./ml) (which had been stored for 0 to, 28 days and examined at autopsy 20 hours later), the results obtained were about the same, regardless of the duration of storage. Also same results were obtained when five groups of immature rats were treated with 20 I. U. of PMS (in such dissiolution as containing 100 I. U. per ml; observed up to 74 hours after PMS injection), 20 I. U. of PMS plus 25 I. U. of HCG (100 I. U./ml), 20 I. U. of PMS plus 10 I. U. of HCG (100 I. U./ml), and 10 I. U. of HCG (50 I. U./ml), respectively, after storage of these hormones for 0 to 28 days.

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Estrogen and gestagen content in bovine follicular fluid during various stages of estrous cycle were determined by biologically. Determination of estrogen was performed by Sulman's method and that of gestagen by Hooker & Forbes.
1. In ovaries collected from 71 cows in slaughter house, there was no obvious correlation between the stage of estrous cycle and mean number of small follicles less than 9 mm in diameter. Follicles larger than 10 mm in diameter were observed in 90.1% of the animals, but large follicles of 13 to 15 mm in diameter were only in two of 46 animals in postestrus to functional luteal phase.
2. Mean estrogen content in follicular fluid in the estrous cycle ranged from 1.7 to 852.5 μg/l was observed thar the larger follicle had the higher estrogen content. The estrogen level was higher in late luteal phase and estrus phase than in the other stages of estrous cycle. The estrogen content in follicles larger than 10 mm in diameter was 16 to 32 times higher in late luteal and estrous phases than in the other stages.
3. Mean gestalten content in follicular fluid ranged from 21.1 to 169.0 μg/l. The value was higher in larger follicle than in smaller one except in early luteal phase, and it seemd to be higher in estrus and functional luteal phase than in the other stages.

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Histochemical demonstrations were carried out on acid phosphatase, alkaline phosphatase, adenosine-tri-phosphatase, glucose-6-phosphatase, 5' nucleotidase, nonspecific esterase and dehydrogenases such as succinate, malate (NAD, NADP dependent), isocitrate (NAD, NADP), β-hydroxybutylate, lactate, glucose-6-phosphate, glutamate and α-glycerophosphate, using unfertilized, penetrated and pronuclear hamster eggs. Unfertilized eggs were taken soon after ovulation, the penetrated 2 to 3 hours after ovulation, and pronuclear ones 11 to 12 hours after ovulation.
In eggs at every stage, all enzymes mentioned above were demonstrated except glucose-6-phosphatase and 5' nucleotidase which were not confirmed because of their nonspecificity to the substrate. While alkaline phosphatase activity was faint in unfertilized eggs, an increase in intensity was observed in penetrated eggs. As for other enzyme activities, no difference was found among unfertilized, penetrated and pronuclear eggs. In eggs at every stage, activities of malate and lactate dehydrogenases were stronger than those of other dehydrogenases. In unfertilized and penetrated eggs, all enzymes except adenosine-tri-phosphate and nonspecific esterase were demonstrated to be spread evenly throughout the cytoplasm, but in pronuclear eggs these enzymes were localized at perinuclear region, and adenosine-triphosphatase and nonspecific esterase were found at the periphery of the cytoplasm, the latter being also distributed in a small amount throughout the cytoplasm.

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Enzymohistochemical demonstrations of phosphatases, nonspecific esterase and dehydrogenases in differentiated 8-16 cell eggs which appear 70 to 76 hours after ovulation were carried out in this study. For comparison, 8-cell eggs before differentiation and early blastocysts were observed.
Phosphatases: In 8-cell eggs, alkaline phosphatase activity was intense, adenosine-tri-phosphatase moderate, and acid phosphatase weak. Acid and alkaline phosphatases were spread throughout the cytoplasm, while adenosine-tri-phosphatase localized near the cell membrane. Concerning differentiated eggs and blastocysts, acid phosphatase activity was much stronger in inner cells than in trophoblasts, while the activities of alkaline and adenosine-tri-phosphatase showed no local differences. With all the eggs from the three stages, the presence of glucose-6-phosphatase and 5' nucleotidase was not confirmed, because they were nonspecific to the substrates.
Nonspecific estearse: In eggs at every stage, nonspecific esterase activity was weak, though it spread throughout the cytoplasm. In differentiated eggs and blastocysts, its activity was stronger in trophoblast than in inner cells.
Dehydrogenases: In 8-cell eggs, activities of malate and lactate dehydrogenases were moderate, while those of other dehydrogenases were weak or feeble. In differentiated eggs and blastocysts, local changes were observed in the strength of some dehydrogenase activities; activities of malate, β-hydroxybutyrate, lactate and a-glycerophosphate dehydrogenases were stronger in trophoblasts than in inner cells of such eggs. As for succinate, isocitrate, glucose-6-phosphate, glutamate dehydrogena-ses, the strength of their activities showed no differences between inner cells and trophoblasts.

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1) It was observed that marked atrophy of testes in adult rats fed 0.1% nitrofurazone for 14 days and the seminiferous tubles contained only spermatogonia and Sertoli cells in 28-day fed rats.
2) Acidophilic degenerated spermatocytes increased at 8 hours after oral administration of nitro-furazone (250 mg/kg) in immature rats.

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[in Japanese]

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