Various routes of administration of LH-RH and its potent analogues, des-Gly¹⁰-LH-RH-ethylamide (analogue I) and des-Gly¹⁰-[D-Leu⁶]-LH-RH-ethylamide (analogue II) were compared for their effectiveness in inducing ovulation in diestrous rats. Irrespective of the routes, analogue II was the most active preparation followed by analogue I and then by LH-RH. Parenteral routes (s.c., i.v., i.p., and i.m.) of administration were markedly effective as compared with other routes of administration. The order of effectiveness among parenteral routes of administration were the followings: LH-RH, i.p. >s.c. >i.v. analogue I, >i.m. or i.v. >s.c. ?? i.m.; analogue II, m. When the intravaginal or intranasal route was used, the amount of ED₅₀ of analogue II was about 8 or 580 times greater as compared to the dose estimated by s.c. injection. But by the intragastric or sublingual route of administration, an enormously large amount of any of these peptides was required to induce ovulation in diestrous rats.

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Antigenicity of luteinizing hormone-releasing hormone (LH-RH) and its potent analogues des-Gly¹⁰-LH-RH-ethylamide (analogue I) and des-Gly¹⁰-[D-Leu⁶]-LH-RH-ethylamide (analogue II) was studied by means of the active anaphylactic and passive cutaneous anaphylactic (PCA) tests.
In the active anaphylactic test using gninea pigs, sensitized animls with LH-RH, analogues I and II showed mild reactions similar to the anaphylactic symptoms (hyperemia of ear lappet, shiver-ing, urination or defecation) when the corresponding compounds were challenged, but the same reactions were equally observed with these compounds in unsensitized intact animals. Thus, it is concluded that the reactions were not induced by antibodies produced but by the inherent disposi-tions of these compounds.
In the PCA test, two rabbits for the respective compounds were sensitized by eight repeating intradermal and intramuscular injections, and one intravenous booster injection with these compounds. PCA reactions were examined in guinea pigs for the sera thus obtained. Both of the sera prepared by the LH-RH injection produced a moderate PCA reaction. One serum prepared by analogue I produced a false positive, but the other showed no reaction. Neither of the sera by analogue II produced the reaction.

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Strain difference in the maternal behavior pattern was studied using ICR, C57BL/6, C3H/He and IVCS¹⁾ female mice aged from 10 to 12 weeks. The maternal behavior of each test animal was observed for 5 minutes after contact with the pup.
The results obtained were as follows; 1) As to the ratio of initial retrieving, IVCS strain (0.7 %) was significantly lower (p<0.001) than other strains (42.3 to 72.2%). 2) One maternal behavior was observed in ICR (30.8%), C3H/He (5.6%) and IVCS (34.1%), but not in C57BL/6. 3) Four maternal behaviors were observed in ICR (7.7%), C57BL/6 (72.2%) and C3H/He (27.8%), bur not in IVCS. 4) As to the ratio of lactation-position, IVCS strain (0.7%) was significantly lower (p at least <0.01) than others (23.1 to 72.2%).

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The effects of catalase with and without reduced glutathione (GSH), ethylenediaminetetraacetate (EDTA) or sodium laurylsulfate (SLS) in diluent on the survival and acrosome system of boar sper-matozoa stored at 4°C were investigated. Semen was collected from 4 Landrace boars by the manual method and only sperm-rich fraction was used. The basic diluent for all experiments contained 20 ml egg yolk, 1.075 g Tris, 0.533 g citric acid, 2.667 g glucose, 100, 000 I.U. potassium penicillin G and 0.1 g dihydrostreptomycin sulfate per 100 ml of diluent. The sperm samples were cooled to room temperature (1823°C) at a constant rate of 0.33°C per min, centrifuged for 1015 min at 600 g and resuspended in the basic diluent to give a concentration of 10 × 10⁸ cells per ml. The sperm suspen-sion was diluted 1:4 (suspension: diluent) with the diluent containing different levels of catalase and/or other agents and gradually cooled to 4°C over 4-h period. After 5, 10 and 15 days of storage at 4°C, sperm motility was assessed microscopically at 15-min intervals during incubation at 37°C for 6090 min. Acrosome morphology of spermatozoa was assessed after staining in a 7.5% (V/V) buffered solution of Giemsa stain. In experiment 1, the effects of 0, 37.5, 75, 150, 300, 600 and 1200 Sigma Units (S.U.) of catalase per ml of diluent on sperm survival were compared. All levels of catalase improved sperm survival during storage for 15 days. The best results were obtained at concen-trations of 751, 200, 1501, 200 and 150600 S.U./ml for spermatozoa stored for 5, 10 and 15 days, respectively. In experiment 2, the effect of different levels of catalase (0600 S.U./ml) on acrosome morphology of spermatozoa were compared. The addition of catalase improved the maintenance of acrosome integrity of spermatozoa and the concentration required for maximum percentage of sper-matozoa with normal acrosome was 150600 S.U./ml. Unusual stainability of the anterior boundary of acrosome was the major morphological change observed following storage, and the percentage of spermatozoa with such damage was decreased with catalase levels higher than 75 S.U./ml. The results of these experiments suggest that a catalase level of 150300 S.U./ml is optimal for preserv-ing boar spermatozoa under conditions employed. In three other experiments, the effects of catalase (300 S.U./ml) in diluent containing different levels of GSH (0, 5, 10 and 20 mM), EDTA (0, 2.5, 5 and 10 mM) or SLS (0, 0.02, 0.04, 0.08 and 0.16% W/V) on sperm survival were examined. Again, the addition of catalase improved sperm survival. GSH and SLS also prolonged sperm life when they were used singly, but the beneficial effect of these agents was reduced more rapidly than that of catalase alone. Furthermore, both GSH and SLS had no beneficial effect when they were combined with catalase. EDTA was not beneficial to sperm survival regardless of the presence or absence of catalase.

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Effects of HCG and prolactin on the activities of Δ⁵-3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD and 20α-HSD in pronuclear hamster eggs were histochemically observed in vitro. When eggs were immersed in one of the solutions, each containing 5 i.u., 50 i.u. or 100 i.u. of HCG, the activities of Δ⁵-3β-HSD with dehydroepiandrosterone (DHA) or pregnenolone as the substrate, 17β-HSD with testosterone, and 20α-HSD with 20a-hydroxyprogesterone, were stimulated: the more was the amount of HCG in the solution, the stronger the activity was. With estradio1-17β as the substrate, the activity of 17β-HSD was not stimulated. Immersed in a solution containing either 5 i.u., 50 i.u. or 100 i.u. of prolactin, the activities of 17β-HSD with testosterone as the substrate and 20α-HSD with 20α-hydroxyprogesterone were stimulated: the more was the amount of prolactin in the solu-tion, the stronger the activity got. The activities of Δ⁵-3β-HSD with DHA or pregnenolone as the substrate, and 17β-HSD with estradiol-17β, were not stimulated.

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An experiment was conducted to compare several methods of synchroni-zation of estrus by means of progestogen alone or prostaglandin F_2α (PGF_2α) associated either with or without progestogen.
Two hundreds and forty Merino ewes were divided into 6 groups: Group 1 was control, Group 2 was treatment of 16 mg PGF_2α intramuscularlly at the unknown stages of the estrous cycle, Group 3 was treatment of intravaginal sponge impregnated with 60 mg 6-methyl-17-acetoxyprogesterone (MAP) for 13 days, Group 4 was treatment of intravaginal sponge impregnated with 60 mg MAP for 7 days and 16 mg PGF_2α intra-muscularlly at the removal of sponges, Group 5 was treatment of intravaginal sponge impregnated with 500 mg crystal progesterone for 13 days, and Group 6 was treatment of intravaginal sponge impregnated with 500 mg crystal progesterone for 7 days and 16 mg PGF_2α intramuscularlly at the removal of sponges.
In group 1 (control), only 67.5% of 40 ewes had been exhibiting estrus during the 17 days. The percentages of ewes showed estrus for 7 days after treatments were 60.0%, 67.6%, 77.5%, 61.1% and 65.0% in groups 2, 3, 4, 5 and 6, respectively. Overall, there was no significant difference between the five different methods of syn-chronization (X²=3.45, d.f. 4), although group 4 (MAP-FPGF_2α) appeared to be better than other methods (77.5%). The pattern of synchronized estrus in the groups treated with PGF_2α became wider than that of groups treated with intravaginal sponges im-pregnated with progestogens.
From the results obtained, PGF_2α treatment associated with MAP intravaginally for 7 days, appeared to be more effective methods than the treatment of PGF_2α or progestogen alone for the control of estrus in cycling ewes.

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Weights of fetuses in JCL-ICR mice were studied in relation to the litter size and denaturating fetuses. Virgin females of mice were injeced with 5 IU of PMSG, followed 48 hours later by 5 IU of HCG, paired with males, and examined the following day (day 1 of gestation) for vaginal plugs. On day 14, 15, 16, 17, 18 and 19 of gestation, females were killed and the number of fetuses was recorded. Each live fetus in each horn was weighed to the nearest 0.01 g. One hundred and thirty eight of 314 mated mice beared live fetuses at the time of autopsy. Data derived from the 138 pregnancies were analysed. Out of a total of 1868 fetuses obtatned from 138 mice, 1806 were live fetuses, and 62 were denaturating; 844 live fetuses were in the left horn and 962 were in the right. The average number of live fetuses per mice was 13.0±4.9 (left: 6.1±2.6, right: 6.9±2.9) and the greatest number of live fetuses in pregnant mice was 32 and the smallest number was 2. The mean weight of live fetuses in mice having 812 live fetuses was greater than those in mice having 27 and 1432 fetuses. This suggesed the existence of the optimal number of fetuses for the fetal growth. The values calculated by the formula shown in table 1 were greater when the difference in the fetal number between the right and left horns was 5 on day 16, and 3 on day 19 of gesta-tion. The mean weight of live fetuses in mice having 3 or more denaturating fetuses was signifi-cantly smaller than that in mice having no denaturating fetuses.

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Progesterone and estradiol-17β contents were determined by radioimmunoassay in ovarian cyst-fluid and normal follicular fluid at the different stages of the estrous cycle in the cow.
Cyst-fluid samples contained significantly large amounts of progesterone when compared with values in normal follicular fluid, whereas the mean values for estradiol-17β in cyst-fluid were within the ranges found in normal follicular fluid.

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Embryos were recovered non-surgically 7 days after estrus from superovulated three donor heifers. Transfers were carried out with a modified insemination instrument for 0.25ml capacity straw through the cervix. One morula or early blastocyst was transferred to each of ten recipient heifers. Four recipients were diagnosed as pregnant by rectal palpation at 33 and 53 days after the embryo transfer.

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This experiment was a trial for the production of maximum superovulation in the adult Mongo-lian gerbil using PMS and HCG.
Two-to four-month old Mongolian gerbils, regardless the stages of their estrous cycle, were given subcutaneously of 10-50 iu PMS followed by 10-50 IU HCG 54 hr later. The maximum superovulatory response was obtained in the group receiving 20 IU PMS and 20 iu HCG, and the average number of ova ovulated in 2-, 3-and 4-month old gerbils were 31.4, 26.8 and 24.6, respectively.
Two-month old gerbils pretreated with 20 IU PMS were given 20 IU HCG at 44 to 66 hr after PMS. The large numbers of ova were produced in the groups given HCG at 4854 hr after PMS.
Ovulation began 10 hr and was virtually completed by 15 hr after HCG in gerbils pretreated with PMS.

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