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Deoxyribonuclease (DNase)-like enzyme activity in the semen of stallion, bull, boar, goat, rabbit and rooster was investigated by using deoxyribose determining method in the acidsoluble fraction. The results obtained were as follows.
1. In every animal or bird, DNase-like enzyme activity was mainly detected in seminal plasma, and only traces of the activity were detected in Ringer-extract from spermatozoa.
2. The nature of these activity in seminal plasma was quite similar to those of DNase I and II in most species except stallion. Namely, the optimal pH for the activity was demonstrated at about pH 7 and pH 5, but in the case of stallion it was located in the range of pH 6 to pH 8. When inhibitors of DNase I and II, namely sodium citrate and magnesium sulfate, were added to the reaction mixture, the inhibitory effect was strongly demonstrated in most species, but in the case of stallion the effect was very slight.
3. When buffer solution of pH 7 was used, DNase I-like enzyme activity of seminal plasma was stronger in stallion, rooster and goat than in bull and rabbit, and there was little of the activity in boar. When buffer solution of pH 5 was used, DNase II-like enzyme activity of seminal plasma was stronger in stallion, rooster, goat and rabbit than in bull and boar.
4. The origin of DNase I-like enzyme activity was inferred to be cauda epididymis. In a case of stallion, however, very strong activity was shown in the sucrose extract of seminal vesicle. DNase II-like enzyme activity was originated in all of the reproductive organs except the secretion of boar seminal vesicle, in which little activity was demonstrated.

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With reference to DNA stability of spermatozoa, the amount of diphenylamine-positive materials (DPM), which were presumed to be mainly, DNA-deoxyribose, were investigated in seminal plasma and in spermatozoal acid-soluble fraction during in vitro storage of semen of the five species of animals. The results obtained were as follows.
1. In the semen samples immediately after collection, various amounts of DPM appeared in both fractions in every animal examined. Especially in stallion seminal plasma, there was demon-strated highest content of DPM per 10⁸ sperm.
2. During storage of raw semen at 4°C or 15°C (only for boar semen), the increase of DPM in seminal plasma was demonstrated significantly in rooster (after 4 hours), stallion and rabbit (after 48 hotrs), but the difference was not significant in bull and boar during storage for 48 hours. The amount of DPM in acid-soluble fraction did not vary significantly during storage of semen in every case of animals.
3. When raw semen was stored at 4°C after freezing in the liquid nitrogen for 5 minutes and thawing at room temperature, the increase of DPM in the seminal plasma was accelerated in rooster and stallion. But no effect was observed in rabbit, bull and boar.
4. When total amounts of DPM of both fractions were compared, the tendency of variation was almost similar to that in seminal plasma, but in stallion the variation in total was demonstrated earlier than in seminal plasma, and no variation was observed in the rabbit.

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Embryological changes of implanted eggs in mice treated with superovulation treatment (S. O.), S. O. + progesterone, and S. O. + prolactin were observed using the mice on the 7th day after conception. The results obtained were as follows:
1) Normal developmental stage of implanted eggs was that of egg cylinder. Retarded eggs such as small egg cylinder, early egg cylinder and later blastocyst were also found all through the experimental groups.
2) The retarded eggs appeared more frequently in mice with S.O. treatment, as compared with naturally pregnant mice. Among treated mice, the mice treated with S. O. + prolactin showed the least number of retarded eggs, suggesting some good effect of prolactin on the egg development.
3) It was not necessarily comfirmed that the more the implanted eggs, the more the retarded ones.
4) Retarded eggs were found either distributed in both uteri, or only in one of them. They were frequently found at the region near the ovary or near the vagina, more near the ovary than vagina.
5) Development of the decidual membrane in the implanted uterus was good on the whole. On the contrary. it hardly or not at all develoned in the implantation-failing uterus.

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Upon the administration of large doses of zinc salt simultaneously with cadmium, PARIZEK noted complete morphological protection of the testicular damage by cadmium in rat. The question then arises where zinc salt protects from testicular damage. In order to determine the sites of protective action of zinc against the injurious effect of cadmium, the following experiment was made.
One group of male Wister rat (250270 g of body weight) was given a single subcutaneous injection of 1.5 mg. of cadmium chloride. The second group recieved, previously to cadmium, 100 mg of zinc chloride subcutaneously. The third group of males was served as controls. Autopsy was done at three days after cadmium administration. All the animals were supplied drinking water with warfarin sodium (10 mg/l) daily for four days until they were killed.
In the testes and capute epididymides of cadmium-treated rat, it was demonstrated specific anti-coagulant bleeding by warfarin sodium, although there were no alternations histologically in blood vessels, interstitium and seminiferous tubules of zinc-treated rat testes in addition to cadmium.
It is suggested that the walls of blood vessels in testicular interstitium may be the sites of zinc protection from cadmium-induced damage in rat.

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[in Japanese]

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