Transcervical technique for bovine embryo transfer, using an insemination instrument (50 or 65 cm in length) for 0.25 ml capacity straw was compared with flank surgical or cervical bypass transfer techniques. Embryos were recovered non-surgically six to seven days after estrus from superovulated ten donor heifers, and maintained in BMOC-3 until ready for transfer. Single embryo was transferred to the horn ipsilateral to the corpus luteum in each of 48 recipient heifers which were ±1 day of heat synchrony with the donor heifers. Pregnancy was diagnosed by rectal palpation at 33 and 53 days after the embryo transfer. The pregnancy rates after transcervical, flank surgical and cervical bypass transfers were 31.6% (6/19), 55.6% (10/18) and 18.2% (2/11), respectively.

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The influence of estrogen on the milk quality was studied on the mammary glands of goats in-fected with Staphylococcus aureus 209-P strain.
The goats were divided into two groups of four goats each. In one group, estradiol monobenzoate in sesame oil (300 μg/goat) was injected subcutaneously daily for 5 consecutive days. In the control group, the goats were injected vehicle only. In earch goat, the right side mammary gland was inocu-lated with 70 billion of bacteria in 1 ml of bouillon, via teat canal (EB and B groups). The gland of the other side was served as the control (E and C groups). The milk samples for analysis were taken from each teat 0, 24, 48, 72 and 168 h after the bacteria inoculation.
The number of bacteria in the milk of EB and B groups increased 24 h after the bacteria in-oculation. Then, the number of bacteria tended to decrease, and again, increased 1 week after the inoculation. No significant changes were observed in pH of the milk.
There was similar tendency between EB and B groups in the changes of sodium (Na) and chlorine (Cl) concentrations in milk. The highest levels of Na and Cl were found in both groups 24 h after the inoculation of bacteria. Then, Na and Cl decreased to the control level within 72 h after the inoculation, and increased again 1 week later. On the contrary, the level of potassium decreased in the EB group.
Though the differences in the changes of milk qualities were not significant, the E and C groups were less evident than EB and B groups.
The kallikrein levels in milk were elevated in the increasing order of EB, B and E groups (0.05 μg/ml).

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Immature male rats hypophysectomized at 26 days of age were injected subcutaneously with (1) NIH-FSH (200μg), (2) testosterone propionate (TP, 800μg), (3 )FSH (200μg) plus TP (800μg) oncea day for 50 consective days after an interim of 30 days from hypophysectomy. They were examined for the effects of these hormones on spermatogenesis.
(1) The testes increased slightly in weight in rats treated with FSH or TP alone, as compared with those of hypophysectomized control rats. Further weight gain was achieved by administration of FSH plus TP.
(2) Spermatogenesis was arrested at the primary spermatocyte stage in 99.5% of the semini-ferous tubules in rats treated with FSH or TP alone. On the other hand, in the group of rats inject-ed simultaneously with FSH and TP, there were a few seminiferous tubules containing step 19 sper-matids and a remarkable increase was observed in step 7 spermatids, as compared with the group injected with FSH or TP alone. The development, of spermatocytes in transitional form and the process of metamorphosis from step 17 spermatids were very poor in the rats treated with FSH plus TP, as compared with the intact rats of a normal control group at 107 days of age.
(3) A few spermatozoa apPeared in smears prepared from the cauda epididymidis of the rats treated with FSH plus TP. Most of them carried degenerative characteristics.
(4) Androgen concentrations of blood in the rats treated with TP, and FSH plus TP (testos-terone; 23.7 and 18.0 ng/ml, and dihydrotestosterone; 0.98 and 1.72 ng/ml, respectively) were higher than those in the rats treated with FSH alone and in control rats at 107 days after hypophysectomy.
(5) I twas suggested that the conversion system of testosterone to DHT in addition to the direct effects of FSH and TP might be played on important role for the production of spermatozoa and preservation of their fertilizing capacity. Spermatozoa were produced by simultaneous injection with FSH and TP for a long time, but they were small in number and lacking in viability.

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Autoradiographic study using ³H-6-thymidine was carried out to investigate the effect of estrogen on the induction of DNA synthesis in uterine endometorium of ovaryectomized rats. Wistar strain rats weighing about 200 g were ovaryectomized, and 16 days later, a single dose of estradio1-17β was intramuscularly administered.
1) 3H-6-thymidine uptake by the endometorium after a single injection of 10 μg estradiol-17β was determined by in vivo and in vitro methods, and there was no difference between the two.
2) DNA synthesis was specifically increased in the surface epithelium after administration of estradiol-17β but no significant increase was observed both in stroma and glandular epithelium.
3) Change of the ³H-6-thymidine up take after a single injection of estradio1-17 β was examined, the maximum up take was detected 24 h after the injection.
4) A dose of 10 μg estradio1-17 β could induced the maximum up take of the labelled thymidine by the surface epithelium.

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Growth pattern of the genitalia of the heifers of Japanese Black breed was investigated from birth to puberty. Results obtained in this study are as follows; 1. All heifers whose body weight reached 257-260 kg, had maturated sexually. At puberty, their uterine and cervical weights distributed 78. 0-139. 0 g and 22. 0-85. 0 g respectively. Uterine weights at puberty were about thirty times as heavy as those of neonatal heifer, and the outer di-ameters of uterine horn were about 2 cm. All heifers in this study needed at least 300 days for reach-ing their puberty. 2. At the puberty, the paired ovarian weights distributed from 4.9 to 10. 3 g, being 2-3 times larger than those of neonatal heifers. 3. At the puberty, the paired oviductal weights were about 2 g, and the oviductal lengths became about 20 cm. These values were about two fold of those found in neonatal heifers. 4. The body weight of the heifers showed continual increase after puberty, while there were a little increase in the uterine and cervical weight, and no growth of the oviduct either in weight or length.

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The uterine growth of Japanese Black heifers from neonatal (3-days old) to pubertal stage was studied histologically. Results obtained in this study are as follows.
1) The uterine gland was not observed in an uterus of the 3-days old calf. The initiation of a development of the uterine gland was observed in a superficial zone and also partially in a basal zone of the endometrium in a 29-days old calf. Subsequently uterine glands continued to develop in both superficial and basal zones of the endometrium with the advance in age unitil puberty.
2) At the prepubertal stage, the thickness of the endometrium exceeded that of the myometrium and the thickness of both layers increased gradually with the advance in age. At puberty, the thick-ness of each layer slightly exceeded 3 mm.
3) The height of the endometrial epithelium in the intercaruncular zone was taller than that in the caruncular zone through prepubertal to postpubertal stage. At the postpubertal stage, endometrial epithelia in both zones were mostly composed of columnar cells.
4) It was suggested that in the nulliparous adult heifers, the uteri remained almost unchanged histologically irrespective of age.

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The present study was conducted to evaluate the correctness of the early diagnosis of pregnancy in sows by an ultrasonic echo beam analyzer introduced by LINDAHL et al. A sum of 390 cases of preg-nancies were diagnosed in 182 sows kept at National Institute of Animal Industry, Ibaraki Branch of National Shirakawa Livestock Breeding Station and some commercial farms. The analyzer was applied to the flank of sows at a standing position in the pen or stall without use of any restraint.
In few cases pregnancy was diagnosed ealier than 25 day of gestation and the correctness in-creased thereafter to 93100% 30 day onward. The correctness of the diagnosis was tested in 6 sows at estrus and 50 sows in other stages of the estrous cycle. Six cases of the latter group were diagnosed falsely as pregnant. Some of these errors may be eliminated by repeated tests.
Time required for diagnosis was very short: 91 animals were diagnosed within an hour.
For the early diagnosis of pregnancy in sows, the ultrasonic echo beam method would be practical, convenient and reliable in field conditions.

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Histochemical demonstration of prostaglandin dehydrogenase activity in hamster eggs during their folliculogenesis was made using PGE₂ or PGF_2α, as the substrate according to the method of NISSEN and ANDERSEN. The enzyme activity was negative in the eggs in primary follicles, but became positive in those in small secondary follicles though the activity was rather weak. The activity which was still weak in the eggs in large secondary follicles had grown much stronger in those in antral follicles. The results thus show that prostaglandin metabolism may be absent in hamster eggs at their earlier stages of folliculogenesis, but becomes stronger during the later stages of it.

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In April and November, effect of PGF_2α on the release of prolactin (PRL), growth hormone (GH), and thyrotropin (TSH) was studied in Holstein dairy heifers. In early April (daylight length, 13 h; mean ambient temperature, 8.6°C), a single intramuscular injection of PGF_2α (40 μg/kg bw; 12-20 mg per heifer) was given to 3 heifers, and the same dose was injected to 4 heifers in early November (daylight length, 10.6 h; mean ambient temperature, 18°C). Blood samples were collected from a catheter previously inserted into one of the jugular veins. Injection of PGF2a resulted in an acute elevation of plasma PRL within 15 min. The peak PRL levels were 266±78 ng/ml (Mean±SE) and 70.7±3.7 ng/ml in April and November, respectively. The plasma PRL levels in April during 15-60 min after PGF_2α injection were significantly higher than those in November (p<0.05-0.01), though there was no difference between the pre-injection levels. Although some individual variation was found in the response, no significant rise of plasma GH after PGF_2α was obtained. Plasma TSH con-centration was unaffected by PGF_2α injection both in April and November.

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Some chemical compositions of epididymal fluids of different segments were investigated in twenty boars of Landrace breed. Samples were collected postmortem from the proximal to distal segment of caput (E₁: efferent duct of testis, E₂: initial segment of epididymal duct) and cauda epididymidis (E₃: segment of epididymal duct, E₄: end segment ofepididymal duct), and sperm concentration (spermatocrit), dry weight of spermatozoa, fluid concentrations of sodium, potassium and total protein were measured.
The volumes of epididymal fluid decreased in segment E₂, and increasedagain slightly in segments E₃ and E₄. The concentration of sodium decreased significantly during passage through the epididymis. The changes in potassium, spermatocrit and total protein were similar during the passagethrough the epididymis, and reached the highest value in segment E₂. The increase in dry weight of spermatozoa as their traverse in the epididymis, showed the highest value in segment E₃, which suggested the progress ofresorptive function in the epididymis. Negative linear regressions were obtainedbetween the spermatocrit and the sodium concentration in segments E₂ and E₄, and regressions were positive between the spermatocrit and thetotal protein con-centration in segment E_l and the dry weight ofspermatozoa in segment E₂. Significantly positive correlations were observed between the potassium and the total protein con-centration in the three segments excepts egment E₄ It is suggested that the increase in the potassium and the total protein concentration in segment E₂ are resulted from those in the sperm cells.

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The effects of reversed lighting regime on the timing of parturition were studied in rats whose litter sizes were surgically adjusted on day 8 of pregnancy. The rat was subjected to the standard lighting regime of 14:10 h light-dark cycle, lights on 06.00 h. After operation on day 8, the rats were transferred to another animal room where the lighting regime only was reversed, i.e. lights on 18.00 h. Delivery in these rats was observed between 18.00 h of day 22 and 08.00 h of day 25 of pregnancy and there was an inverse relationship between the gestation period and the litter size. The time of parturition was concentrated in the light period despite of the fact that parturition occurred on the different day of pregnancy. This distri-bution of the time of parturition tended to delay by 12 h from that obtained in the previous experiment in which animals were kept under the standard lighting regime throughout the gestation period. Such prolongation of the gestation period resulted in an increase in the birth weight of litter. The present result that the shifting of lighting regime could affect the time of parturition strongly suggests that a photo-periodic regulation is involved in the onset of parturition in rats.

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Histochemical and scanning electron microscopic observations were made on the spherical sub-stances which occurred in boar seminal gel.
The substances with approximately 20μm in diameter were distributed all over the gel surface.
They consisted of numerous granules of the nature of glyco-lipoprotein. Scanning electron microscopy showed that morphologically normal sperm could pass through these substances.

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