In order to make experimental animals of Japanese cat (felis catus), we reproduced them in small private cages. The origin of our colony consisted of 14 adult females and 4 adult males purchased from dealers. Each of them was kept in a private punched metal cage (35 × 50 × 42 cm) with a metal net floor at 22 to 26° in an atmosphere of 50 to 60% humidity with 14 hours of light daily from 5 a.m. except in 1969, when they were maintained with only 12 hours of illumination from 6 a.m. The animals were supplied with pellet cat chow and water ad libitum. A queen showing the vaginal estrus was mated with a tom in a mating cage and the first day when sperms were detected in the vaginal smear was designated as day 0 of pregnancy.
Results obtained were as follows.
1. For the past three years, the total number of queens mated was 124. They mated in every month and more frequent matings were observed from October to December than in the rest of the year.
2. The total number of labors during the past three years was 84. Parturitions were observed all the year round but they occurred at higher rate in August, November, December, January and May than in the other months.
3. Since kittens born before day 60 of pregnancy were not brought up without artificial aid, the gestation period of 60 days or more was regarded as full. The average and the mode of full gestation period were 64.9±1.6 and 65 days, respectively.
4. The average age of the queens which mated for the first time was 329.0±90.8 days.
5. The average interval between the day of weaning (35 days post partum) and that of the subsequent mating was 48.1±37.2 days.
6. In the dams which did not suckled their kittens, the average interval between the day of parturition and that of the following mating was 21.9±17.1 days, much shorter than in dams lactating.
7. The aberage interval between the day of the first mating, which proved infertile, and that of the next one was 72.9±31.9 days.
8. The first matings of queens resulted in 67% labor at full term, 3% premature labor, and 30% abortion or infertile copulation.
9. Matings of multiparous queens resulted in 74% labor at full term, 3% premature labor, and 23% abortion or infertile copulation.
10. The average litter size was 3.1±1.0 for the past three years.
11. The mortality rates of the respective age groups were as follows: 0 to 5-day-old 14%, 6 to 35-day-old 7%, 36 to 60-day-old 11%, 61 to 100-day-old 3%.

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The ovulatory response was examined in the adult Japanese cat using various kinds of gonadotropins.
Results obtained are summarized as follows.
1. In diestrous cats, estrus was induced 3 days after the combined treatment of 100 IU PMS followed by 50 IU two days later.
2. In PMS-induced estrous animals, ovulation occurred in all of the animals 36 hrs after the single sc injection of gonadotropin (porcine FSH, ovine GTH or HCG), but none ovulated 27 hrs after the treatment.
3. For induction of ovulation in 50% of the animals, the amount of porcine FSH, equine LH, unfractionated ovine GTH, HCG or synthetic LH-RH was estimated as 0.075 AU, 1200 μg, 0.0234 RU, 6 IU or 4.8 μg, respectively.
4. The amounts of various kinds of gonadotropins estimated for induction of ovulation in 50% of diestrous mice were defined as one unit, and the amounts of gonadotropin were compared for their effectiveness in inducing 50% ovulation in various kinds of animals: the amount of FSH in rats, rabbits or cats was estimated as 6, 51, or 7, respectively; that of LH as 12, 96 or 48; that of ovine GTH as 7, 254 or 4; that of HCG as 16, 131 or 8; that of LH-RH as 16, 32 or 128.
These data suggested that LH and LH-RH are less effective for induction of ovulation in cats than FSH, ovine GTH or HCG.

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Previous reports presented that the single injection of clomiphen which is known as an antiestrogen blocks PMS-indubed ovulation in immature rats, showing 24 hours delay of ovulation.
The present experiment was desinged to determine the pattern of serum LH in these rats in order to clarify the time of the LH surge for ovulation. PMS (3 IU) was subcutaneously injected to female Wistar rats at 10:00 AM on 2426 days of age. Clomiphene (Clomiphene-citrate : 2.5 mg/100 g b.w. in 30% ethanol-saline solution) was subcutaneously injected 6 hrs after PMS. Blood was collected by decapitation under ether anesthesia at various times as shown in Table 1. At autopsy ovarian and uterine weights were recorded and oviducts were examined for ova under the dissecting microscopy.
Serum LH levels were measured by radioimmunoassay.
Resuts are as follows:
1) Ovulation rates were 5/5 in PMS-treated group (control), and 0/5 in clomiphene-treated group, 72 hrs after PMS. But 5 out of 6 treated with clomiphen ovulated 96 hrs after PMS.
2) After 48 hrs of PMS injection significant decreases of uterine weights were observed in clomiphene treated groups as compared with PMS-treated controls (P <0, 01).
3) Highly elevated levels of serum LH were found during 5462 hrs in PMS-treated controls and during 7879 hrs in the clomiphene group, indicating 24 hours delay of LH discharge in the latter.
The anti-estrogen drug may affect estrogen-receptors in the CNS-pituitary axis responsible for the LH surge on the second day-afternoon in these immature rats.
The authors acknowledge the gift of rat LH radioimmunoassay materials from the Rat Pituitary Hormone Distribution Program of the National Institute of Arthritis, Metabolism and Digestive Diseases.

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Histochemical demonstration was carried out of nucleic acids, proteins, polysaccharides, lipids, acid and alkaline phosphatases, esterase, succinate dehydrogenase, and various kinds of hydroxysteroiddehydrogenases in primary and secondary giant cells from hamsters 5.5 to 16 days of pregnancy.Primary and secondary giant cells were classified so according to Orsini's division(1954)
.primary giant cells extending cytoplasmic processes were observed in the decidua near the ecto-placental cone and around the implantation cavity, which later increased in number to form a net-work in the decidua capsularis near the Reichert membrane.Frequently, these giant cells containedthe debris of erythrocytes in the cytoplasm.In the last stages of pregnancy, they became spindle-like in shape and decreased in number.Secondary giant cells, polygonal in shape, appeared abundantlyover the outer surface of the proliferating ectoplacental cone 7.5 days of pregnancy, and they subse-quently constituted the trophospongium.
Both primary and secondary giant cells, including trophospongium cells, always contained a largeamount of RNA and a small amount of acrolein-Schiff positive proteins.Primary giant cells possess-ed a small amount of glycogen granules for the first 12 days of pregnancy and asmall amount oflipid droplets for 8 days, both substances disappearing thereafter.Meanwhile secondary giant cellscontained a small amount of glycogen granules for the first 13 days of pregnancy, and a small amountof lipid droplets for 10 days, which increased thereafter.Both types of giant cells showed a weakactivity of acid phosphatase and of succinate dehydrogenase throughout pregnancy, and a weak ac-tivity of alkaline phosphatase for the first 8 days, which disappeared thereafter.They showed noactivities of esterase nor any kind of various hydroxysteroid dehydrogenases.
From the results stated above, it can be proposed that(1)the hamster giant cells, having thenature of migration and phagocytosis, participate in the implantation of blastocysts and in the en-largement of implantation cavity, and that(2)they do not seem to produce progesterone.

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The sex ratios of livebirths and stillbirths in swine were studied with data collected from theformer Koyasu-Noen Farm. A total of 17, 363 animals were examined. They consisted of 12, 785 ofthe Yorkshire breed (Y) and 4, 578 of the Berkshire breed (B). Analysis on sex ratio was performedby the same methods as described in the previous paper.¹⁾ The classes which showed a shift of sexratio to either sex were cited mainly in tables. The results obtained are summarized as follows.
The total sex ratio in the two breeds as a whole was 51.8% ( ?? %) and showed a shif t to maleat a 1% significance level. The sex ratios were 51.7 and 52.7% in the Y and B, respectively (Table1). The paternal and maternal individuals which showed a shift of sex ratio in their offspring were9.4 and 6.5%, respectively (Tabies 2 and 3). Their pedigree, however, could not be surveyed. Therate of stillbirths was 7.3% and the sex ratio of stillbirths 55.5% in the two breeds as a whole. Thesex ratio of stillbirths was 54.1% in the Y and 59.3% in the B (Table 4).

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The present experiments were performed to analyze protein components of uterine fluid and theirorigins in early pregnant rats.
1. Changes in the protein contents of rat uterine fluid on Day 3 to 7 of early pregnancy wereshown in Table 1. Much increase in the protein contents of endometrium occurred from Day 3 toDay 4 and from the Day 6 to Day 7, while in the protein contents in uterine fluid gradually increasedup to Day 6 of pregnancy.
2. It was suggested from the results shown in Tables 2 and 3 that changes of the pootein contentsin the uterine fluid and endometrium might be induced by ovarian hormones and decidualization.
3. The protein components of uterine fluid in early pregnancy were examined by polyacrylamidegel electrophoresis at pH 9.1, gel diffusion and immunoelectrophoresis at pH 8.6 (Fig. 13). It wasdemonstrated that most of the protein components of uterine fluid were similar to those of serum protein and suggested that the components of uterine fluid might be originated from the componentsof endometrium.
4. Transport of serum protein into uterine lumen was measured using fluorescein isothiocyanate(FITC) labelled serum protein in early pregnant rats. As shown in Fig. 4, the content of FITC in the serum was constant throughout the period, however, its contents in the uterine fluid became greaterin agreement with the increase of the protein contents in uterine fluid. As noted from Fig. 5, transport of serum protein into uterine lumen was controlled by ovarian hormones.

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[in Japanese]

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