The main factor to maintain or growth of prostate is a testosterone. It is widelyaccepted that testosterone is necessary to be converted to dihydrotestosterone (DHT) to express its effect on the prostate. The 5α-reductase activity is reportedly under the control of the prolactin (PRL) and enhanced by testosterone and PRL, though PRL in the regulation of prostate growth is still controversial. The mastomys [Praomys (mastomys) natalensis] is an experimental animal unique for the female as well as the male having the morphologically functional prostate with two efferent ducts. In the present study, hormonal influence on the growth and maintenance of the prostate gland was studied in the mastomys of both sexes.
Gonadectomized animals were grafted with the pituitary gland or further treated with testosterone or bromocriptine. The prostate weight decreased by castration and the administration of testosterone alone increased the prostate weight in both sexes. Furthermore, the decrease in the organ weights in both sexes due to castration was restored by pituitary graft, and the restoring response was higher in females than in males. Proliferation of epithelial cells was induced by administration of testosterone or grafting the anterior pituitary.

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Reproductive hormone levels and testicular inhibin content in adult rats after theexperimental unilateral and bilateral cryptorchidism were investigated. The weight of abdominally placed testis decreased by about 40% of control testis 2 weeks after surgery. There were no changes in seminal vesicle weight. The cryptorchidism groups exhibited a significant increase in serum FSH levels. In contrast, serum LH level in the unilateral group showed no significant difference from control, while increased significantly in the bilateral group. The levels of serum testosterone in the bilateral group decreased, but not in the unilateral one. The contents of testosterone in the unilateral cryptorchid rats decreased in the abdominal testis and increased in the scrotal. In the bilateral cryptorchid rats, there were no changes in testicular testosterone content. Inhibin contents in the abdominal testis of both unilateral and bilateral cryptorchid rats were significantly lower than control. These results suggest that there is no compensatory function concerning the inhibin synthesis in Sertoli cells, unlike the testosterone production in Leydig cells in the intact testis following unilateral cryptorchidism.

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Two Holstein heifers (Cow 1 and 2) were experimentally exposed to an intermittentnoise, 70-75 phones at 1 hr intervals, throughout an estrous cycle. Duration of estrus, number of ovulation, and blood concentrations of LH and progesterone were compared with those obtained in pre-and post-treatment estrous cycles. The results obtained in the three successive estrous cycle were as follows.
1) In the first cycle, pre-treatment control cycle, ovulation was detected by rectal palpation 32 hr after the onset of estrus in both the two heifers. Typical LH surge, followed by an increase of progesterone during the luteal stage was observed.
2) In the second cycle, the noise-loading cycle, duration of estrus was prolonged as compared with previous cycle and ovulation took place 72 hr after the onset of estrus. Although two ovulations were confirmed in both heifers, LH surge was not observed in Cow 1 during the 60 hr observation period. Blood progesterone level in the subsequent luteal phase showed a normal change.
3) In the third cycle, post-treatment cycle, duration of estrus was reduced toward the pre-treatment value and the ovulation was confirmed 46 hr after the onset of estrus.
The present results indicate that the noise stress can affect reproductive function such as LH secretion, duration of estrus and thus timing of ovulation in heifers.

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Oviduct patency in heifers and cows was studied with kymographic oviduct insufflationapparatus connected to a Foley catheter. In experiment I, a total of 99 oviducts in 55 animals was examined without sedation. Many of the oviducts (88.9%) were patent. For the others, carbon dioxide gas insufflation was discontinued due to a rise of pressure more than 110mmHg (8.1 %), or due to gas penetration into the endometrium (3.0%). Estrous cycle stages and parity had little effect on oviduct patency. The initial mean pressure at passage of follicular and luteal phases in heifers was higher than that in cows. Pressure tracing was classified in the patent group as types I (descending), II (crawling), III (ascending), IV (dropping) and their mixture, while in the penetrated group as types V (dropping) and mixture. The incidence of types I, II and mixture in the patent group was higher than that of other types of pressure tracing, and occupied more than 70% in each groups. In experiment II, 42 oviducts in 21 animals were examined following xylazine pretreatment. The incidence of patent oviduct (92.9%) was higher than that in experiment I. In the remaining oviducts (7.1 %), the gas insufflation was discontinued since the upper limit of pressure was exceeded. No case of gas penetration was found. The initial mean pressure at passage in heifers dropped significantly in follicular phase as compared with that in experiment I. The incidence of types I, II and mixture in the patent group was higher than that of other types of pressure tracing. It is concluded that this oviduct insufflation test with xylazine pretreatment may be safely conducted to examine oviduct patency in living heifers and cows.

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Using prostaglandin (PG) E₂ as the substrate, the activity of NADP-dependent 15-hydroxyprostaglandin dehydrogenase (type II PGDH) in preimplantation rabbit eggs and embryos was histochemically investigated, and the metabolism of PGE₂ in them was discussed. The eggs and embryos observed were at 1-cell (unfertilized and pronuclear) to 8-cell, morula and blastocyst stages. Type II PGDH, as well as NAD-dependent PGDH (type I PGDH), was histochemically detected by the method of Nissen and Andersen (1968). The activity of the type II PGDH was strong in the eggs at 1-cell stage, strong to weak in the eggs at 2-cell stage, and weak from 4-cell eggs to the blastocyst stage. The diformazan granules showing the presence of type II PGDH activity were spread evenly throughout the cytoplasm of eggs and embryos at the stages of 1-cell through morula. Blastocysts also presented such granules spread evenly throughout the cytoplasm of both trophoblast and inner-cell-mass cells. The intensity and the distribution of the type I PGDH activity in the eggs and embryos were similar to those of the type II PGDH activity. These results thus seem to point out that rabbit eggs and embryos do have type II PGDH, as well as type I PGDH which has widely been found in different mammalian embryos.

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The present study was conducted to evaluate developmental ability of mouse half embryos, in which four types of the halves were produced at the two-cell stage by micromanipulation; (1) a nucleus from one of the blastomere was removed (1/2+C), (2) blastomeres of 1/2+C embryos were fused with sister blastomeres by electric stimulus (1/2DC), (3) a whole blastomere of a two-cell embryo was removed (1/2ZP) and (4) the embryo was separated into two zonae-free blastomeres (1/2ZPF). The development of the half embryos to blastocyst and to full term was examined by culture for two days in vitro and by transfer to recipients. The number of TE and ICM cells in the half embryos at early blastocyst stage was estimated by fluorescent staining method.
The results were as follows.
1) The proportions of 1/2+C and 1/2DC embryos developed to blastocyst were quite high, i.e., 97% and 96%, respectively, while the proportion of 1/2ZP and 1/2ZPF embryos was significantly lower, 88% and 87%.
2) Of blastocysts derived from 1/2+C and 1/2ZP embryos, 60% developed to full term after transfer to recipients, but only 30% and 40% was developed to full term in blastocysts derived from 1/2ZPF and 1/2DC embroy, respectively.
3) The total number of cells in 1/2ZPF embryos at early blastocyst stage was significantly low, and the ratio of ICM cells/TE cells of half embryos was not significantly different from control.
These results demonstrate that the developmental ability of mouse 1/2+C embryos to full term is almost equal to that of normal embryos.

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In order to survey the relationship between metabolic activity and developmental ability of fresh mammalian single ovum, we modified an enzymatic cycling method in the present study. We measured 6-phosphogluconate dehydrogenase activity (6PGD) in fresh 1-cell rat ova to examine the effect of pH on 6PGD activity. As a result, 6PGD activity in phosphate buffer solution (PBS) (-) (pH 7.3) and 1.75mM substrate was the highest; i.e, the activity was 166.2±39.9 × 10^-11 mol/ovum/hr (mean±SE). In the new system, PBS (-) (pH 7.3) and 1.75mM substrate were used instead of Tris-HCl (pH 8.0). The activity of 6PGD in rat 8-cell embryos was 101.1±54.6 × 10^-11 mol/embryo/ hr by this method, and 66.7% (4/6) of the embryos developed to blastocysts following measurement of 6PGD activity.

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Effects of progesterone on the function of corpus luteum in estrous cycle were compared between the first and the third estrous cycle after vaginal opening in rats. When 2.5 mg/100 g body weight (B.W.) progesterone was administered between 07:00 and 08:00 hr on the day of estrus or on day 1 of diestrus to rats showing the first estrous cycle, the diestrous period was persisted more than 9 days in 95% of animals. In the diestrous period, plasma prolactin (PRL) level showed daily changes and corpora lutea became functional. The luteal function was enhanced by the deciduoma formed after uterine traumatization on day 3 of diestrus. However, in rats showing the third estrous cycle, 7.5 mg/100 g B.W. progesterone was required to induce similar response to those obtained in the first estrous cycle. Also, no functional corpora lutea and no daily change in PRL secretion were observed in rats injected with progesterone on day 1 of diestrus in the third estrous cycle. These results indicate that progesterone acts more effectively for induction of pseudopregnant diestrus in the first estrous cycle than in the third estrous cycle.

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The influence of the ovum location in a plastic straw during freezing and thawing was investigated as to the morphology of zonae. A fertilized bovine ovum was in a plastic straw by successive aspiration located on cotton-plugs (group I), into the meniscus between two adjacent air babbles (group II) or in the center of 10% glycerol solution (group III) while the straws were kept vertically. In group IV the ovum was attached to the inner wall of the middle portion of 10% glycerol solution while the straws were held horizontally. The straws were cooled to -5°C from room temperature at the rate of 1°C/min. After 5 min the ova were seeded and kept at the seeding temperature for further 10 min, and then were cooled to -30°C at the rate of 0.3°C/min before being plunged into LN₂. The ova thus treated were thawed in the water bath at 37°C and examined for the occurrence of damaged zonae under a stereomicroscope.
The occurrence frequencies of ova with damaged zonae were 42.6% (86/202), 21.6% (22/102) and 22.0% (22/100) for group I, II and III respectively. In group IV the percentage of ova with damaged zonae was as low as 16.2 (44/271). A statistically significant difference was observed between group 1 and II, III and IV.

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