The influence of the age and body weight on PMS-induced ovulation in immature rats was studied. The succeeding estrous cycle after PMS-induced ovulation were also examined. in PMS-treated immature rats.
I. The animals were given a single injection of PMS subcutaneously between 9:0010:00 hr from day 17 to day 26, and were killed 72 hours after PMS to examine oviducts for ova.
None ovulated when PMS was given before day 20 regardless of the amounts of PMS administered. Ovulation was initiated by 3IU of PMS on day 21, 10IU of PMS on day 24, or 30 IU of PMS on day 23.
Bimodal ovulatory effect of PMS on 22-day old Holtzman rats, reported by YING and MEYER (1969), was also observed in 23-, 24-or 25-day old Wistar rats. When PMS administration was delayed until day 26, however, ovulation occurred in all of the animals.
II. The influence of the body weight and days of age of immature rats at the time of PMS treatment on PMS-induced ovulation was also examined. Three IU of PMS was given subcutaneously on day 20, 21 or 22. None ovulated by PMS on day 20, but the heavier group showed a higher ovulation rate by PMS on day 21 or 22 than that of controls. By PMS on day 23, ovulation occurred in most of the animals in controls as well as in the heavier group.
PMS-induced ovulation in immature rats may be dependent upon the days of age rather than the body weight increase.
III. Intact, 25-day old female rats were singly injected with various amounts of PMS and examined. the occurrence of the second vaginal estrus, for which only endogenous gonadotropins are responsible, was examined.
In non-treated controls, the first estrus was observed 37.7±0.4 days of age (mean S. E.) and followed by the second 45.1±0.5 days of age. With 3IU of PMS, the second estrus was observed 38.7±0.5 days of age, 9 days after the first ovulation induced by PMS. With 30IU of PMS, the second estrus was observed 43.1±0.4 days of age with no significant difference as compared with that of controls, though ovulation was regularly induced 28 days of age by that amount of PMS.
It is concluded, therefore, that the first and second estrus were advanced significantly by 3IU ofPMS treatment as compared with those of controls. The advancement of the secondestrus by PMS is assumed to be mediated through the hypothalamus stimulation byincreased release of ovarian estrogens.

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Aldose reductase and ketose reductase (sorbitol dehydrogenase) activities were investigated in bovine endometrium, chorion, and placenta in relation to the carbohydrate provision for embryonic nutriment.
The genitalia was obtained from 29 healthy cows: 21 cows during estrous cycle and 8 cows with known days of gestation.
Two grams of the tissue sample or smaller quantities of the chorion was homogenized, and enzymic preparation was carried out by the method of HÅSTEIN et al. (1968). The assay system for aldose reductase was derived from the procedure of VELLE et al. as described by HÅSTEIN et al. (1968), and ketose reductase activity was assayed at 25°C according to the method of SAMUELS et al. (1962).
1. The activities of aldose reductase and ketose reductase were detected in the uterine endometrium during estrous cycle and gestation, and in the chorion and the placenta.
2. Aldose reductase activity was high in the bovine uterine endometrial tissue at estrus and early luteal stage of estrous cycle, and low at mid-and late luteal stages and during preg-nancy. The rise of the enzymic activity at early luteal stage coincided with the increase of sorbitol concentration in the uterine secretion at the same stage which was previously obser-ved¹⁾, whereas no relationship was found between the enzymic activity and sorbitol level at estrus.
In the chorion, an increase in the specific activity of aldose reductase was observed with advance of pregnancy.
3. Ketose reductase activity was intensely positive in the epithelium of uterine endomet-rium and uterine gland, apical zone of caruncle and trophoblast of the chorion. The enzymic activity was somewhat higher in the chorion than in the uterine endometrial tissue. The con-version of sorbitol to fructose was confirmed by gas chromatography, after incubation of the enzymic preparation from the bovine chorion with sorbitol and NAD.
4. From the distribution and activity of aldose reductase and ketose reductase in bovine endometrium and chorion, it has been shown that sorbitol in bovine uterine milk²⁾ is produced by the endometrium at early luteal stage (estimated day 46 after estrus) and converted to fructose by the chorion during embryonic stage.

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Histochemical demonstration of acid polysaccharides was carried out on hamster eggs just after ovulation through just before implantation, using alcian blue stain. Although no acid polysaccharides were found in the egg cytoplasm at any stage, a large amount was observed evenly spread throughout the zona pellucida of penetrated, pronuclear and cleaved eggs, and somewhat in smaller amount in that of blastocyts. In 8-celled eggs, acid polysaccharides appeared also in the perivitelline space adhering to the blastomere surface, while in naked blastocysts, such substances appeared adhering to the trophoblast surface. This paper dealt with the origin of these acid polysaccharides especially in the perivitelline space as well as their physiological significance.

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It has been reported that boar seminal plasma has a high content of CO₂¹⁾ This study was carried out to examine the influences of temperture, shaking, and pH on the solubility of CO₂ in boar seminal plasma.
Semen was collected with manual method, and was cooled down to 5°C rapidly. Seminal plasma was obtained by centrifuging it (10, 000 rpm) for 20 minutes at 5°C. The amounts of CO₂ was measured with Warburg's manometric apparatus. The pH was measured with glass elec-trode pH meter. The contents of Na and K were measured with atomic absorption spectroscopy.
Experiment 1: Influences of temperatures (20°C and 37°C) and shaking (120 stokes/min.) on the liberation of CO₂ from seminal plasma were examined. Seminal plasma samples (3 ml) were incubated in Warburg flasks (about 20 ml content), and the amounts of CO₂ liberated were measured under the various conditions (Table 1). The liberation was stimulated by shaking or increasing the temperature. Fig. 1 shows the effect of KOH on the absorption of CO₂ liberated from seminal plasma. Seminal plasma samples were incubated in Warburg flasks containing 0.3 ml of 20 % KOH (with folded filter paper) or water in center wells. Vigorous liberation took place at early stage of incubation (Fig. 1; graph 1), hence KOH failed to absorb the liberated CO₂ completely and the pressure in gas phase rose in some cases (Fig. 1; graph 2). The sample shaken during the equilibration showed little liberation during the measuring (Fig. 1; graph 5), and the reading dropped from the start of measuring (Fig. 1; graph 6 and 7) this movement was due to the absorption of CO₂ which remained in gas phase, and not to the respiratory activities^{3), 4)} of seminal plasma.
Experiment 2: Influences of CO₂ liberation on the pH of seminal plasma were examined. The pH of seminal plasma rised with the increasing of the liberation of CO₂ (Fig. 2).
Experiment 3: Contents of CO₂ and pH of seminal plasma were measured before and after shaking (Table 2). The contents of Na and K were shown in Table 3. The coefficients of corr-elation between the measured values were caluculated (Table 4). Significant positive correlations were shown between pH and the contents of CO₂ and those of ions.
Experiment 4. Mcllvaine's phosphate buffer solutions (pH; 6.27.8) and 3 N H₂SO₄ were added to seminal plasma and their influences on the liberation of CO₂ were examined. The additions stimulated the liberation (Fig. 3).

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Spermatogenic actions of HCG, PMSG and testosterone in hypophysectomized adult male rats were investigated by injection with equivalent doses of these hormones (prostate unit : Pr. U.) which has been determined using hypoyhysectomized immature rats.
The weights of the vental lobes of the prostate at the does of 2 (0.4 MU), 3, 6 and 12 Pr.U. of HCG corresponded to those at 3 (2 IU), 5, 6 and 8 Pr. U of PMSG, respectively.
At the dose levels of these hormones corresponding in their potency in hypophysectomized adult male rat, the effect on weights of the testes and accessory reproductive organs was almostly each other. No significant differences in the histological findings of testicular tissue were observed between the doses of HCG 3 Pr. U. and PMSG 5 Pr. U. However, there were significant increase in numbers of preleptotene spermatocytes and the step 7 spermatids in the rats treated with 12 Pr.U. of HCG in comparison with those treated with 8 Pr. U. of PMSG. The size of the seminiferous tubules in the rats treated with HCG was also larger than those treated with PMSG.
These results indicated that HCG had a slightly superior effect on the spermatogenesis to PMSG at the equivalent dose level determined by the weight of the ventral lobes of the prostate in hypophysectomized adult rat. Furthermore, it was confirmed that spermatogenic action of testosterone was inferior to that of HCG and PMSG.

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The present experiment was planned to determine an adequate pre-freezing time for froz-en preservation of drake spermatozoa. Five pre-freezing times of 0, 1, 2, 3 and 5 minutes were set up. The relationship between each pre-freezing time and temperature change in the semen sample was tested by chromel-alumel thermocouple. At the same time effect of the pre-freezing on the sperm motility was examined after freezing and thawing.
Marked difference was found in the change of the semen temperature according to the times of pre-freezing. The temperature of semen sample have shown a sharp fall to -196°C in about 20 seconds when it was exposed to 0 minute pre-freezing. When the samples were exposed to 1, 2, 3 and 5 minutes pre-freezing, each temperature went down about to -11°C -94°C, -149°C and -180°C slowly and when these samples were preserved in liquid nitrogen, the temperature dropped suddenly to -196°C. The sperm motility of these semen samples after thawing were 9, 58, 79, 82 and 80% (over ?? ) in 0, 1, 2, 3 and 5 minutes pre-freezing, resp-ectively.
From these results, it seems that the adequate pre-freezing time in the freezing process of drake spermatozoa is 2 or 3 minutes and it needs not to be over 5 minutes.

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Ovarian activity and estrous cycle following intrauterine injection of prostaglandin F_2α (PGF_2α ) were investigated in the cow.
PGF_2α was injected into the middle portion of the uterine horn ipsilateral or contralateral to the corpus luteum through the cervix using the metal catheter between the very early luteal stage (2 days after ovulation) and the late luteal stage (16 days after ovulation) of the estrous cycle. Ovarian activities were examined every day after the treatment by rectal palpation.
In the cow injected ipsilateraley with 0.5 or 1.0 mg of PGF_2α dissolved in 0.5 ml of aq. distillata on 2 consecutive days, and 3 or 4 mg of PGE_2α dissolved in 0.75 ml of aq. distillata on a certain day between 5 and 16 days after ovulation, precocious ovulation occurred between 4 and 6 days, mostly in 4 or 5 days after the treatment. The corpora lutea of these cows had already begun to regress 24 hours after the treatment, then decreased rapidly in their size followed by follicular development. When the treatment was done at the very early luteal stage of the estrous cycle between 2 and 4 days after ovulation, these drastic changes of ovarian activities were not found. Ovulation occurred between 8 and 22 days after the treatment and the estrous cycle was normal length or somewhat shortened. In a few cases, the corpora lutea seemed to be developed and maintained as those seen in the normal estrous cycle. In most cows, however, such typical changes of corpora lutea did not occured in their developing and regressive process. In some cases, the corpora lutea showed regressive changes during a few days following the treatment, thereafter began to develop again, then maintained as long as normal estrous cycle, otherwise regressed rapidly. The corpora lutea in other cases continued or ceased their develo-pment during a few days following treatment, then regressed rapidly. In the cow injected with 6 mg of PGF_2α dissolved in 0.5 ml of aq. dirtillata into the contralateral uterine horn, ovulation occurred between 4 and 7 days (ay. 6.0 days) after the treatment. Whereas, when 6, 8 or 10 mg of PGF_2α dissolved in 5 ml of saline was used, ovulation occurred 4 or 5 days (ay. 4.3, 4.0 and 4.3 days respecively) after the treatment.
These results suggest that an intrauterine injection of low dose level of PGF_2α into the ipsilateral uterine horn to the corpus luteum during the luteal stage of 56 days postovulation may be applicable to the estrous synchronization of the cow.

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