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Search for other papers by R. W. MOORE in
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Search for other papers by R. L. BRINSTER in
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Summary.
The level of aspartate aminotransferase (AA) activity was examined in the preimplantation embryo, and there was a 29% decrease in total activity from the one-cell stage to the eight-cell stage, and a 153% increase from the eight-cell stage to the late blastocyst.
The affinity of the AA for α-ketoglutarate and aspartate was measured at the two-cell and early blastocyst stages. At the two-cell stage, the enzyme has a higher affinity for aspartate than for α-ketoglutarate while, in the early blastocyst, the affinity was the reverse. It is suggested that this result is compatible with a change from a predominance of the mitochondrial form of AA at the two-cell stage to a predominance of the cytoplasmic form at the early blastocyst stage.
There was also a steady drop (73%) in the total activity of glutamic dehydrogenase from the one-cell to the late blastocyst stage.
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Search for other papers by L. G. Moore in
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Summary. Systemic intravenous infusion of physiological concentrations of PGF-2α and its major metabolite, 13,14-dihydro-15-keto-PGF-2α (PGFM) into non-pregnant ewes possessing a corpus luteum induced the release of oxytocin—neurophysin. These results suggest that, during luteolysis, endogenous release of uterine PGF-2α would be able to stimulate the release of ovarian oxytocin and oxytocin—neurophysin from the ovary.
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Search for other papers by L. Moore in
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The aim of the present study in Booroola ewes, either homozygous (BB) or non-carriers (++) of the FecB gene, was to test the specificity of the pituitary responses to exogenous hypothalamic releasing hormones by examining the plasma concentrations of FSH, LH, thyroid-stimulating hormone (TSH) and growth hormone (GH) after injecting the animals with different doses of GnRH, thyroid-releasing hormone (TRH) or growth-hormone-releasing hormone, (GHRH) which were administered on separate occasions. The animals (n = 8 per dose) received 0, 3.1 or 12.5 μg of thyroid-releasing hormone and GnRH (i.v.), whereas they (n = 9–13 per dose) received 0, 6.0 or 16.0 μg GHRH (i.v.). For each experiment there were no differences between the genotypes in bodymass or age. Gene-specific differences in the mean pretreatment concentrations of plasma FSH (BB > ++; P < 0.05) but not of LH, TSH or GH were noted. After treatment with GnRH, TRH or GHRH, significant effects of dose were noted for all the hormones; however, a gene-specific effect was observed only for FSH in response to GnRH (BB > ++; P < 0.01) with no genotype × dose interaction (anova). For LH, the effects of genotype and the genotype × dose interaction almost reached significance at the 5% level (genotype, P = 0.055; genotype × dose, P = 0.067). For TSH and GH the respective genotype × dose interactions were not significant. These results support the hypothesis that the FecB gene in Booroola ewes influences the release of pituitary hormones in response to hypothalamic releasing hormones only in the case of GnRH, which results mainly in different plasma concentrations of FSH.
Search for other papers by L. DePalatis in
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Search for other papers by J. Moore in
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Search for other papers by R. E. Falvo in
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Summary. Blood samples were withdrawn every 20 min from 3 conscious intact and 2 castrated mature males during non-consecutive periods of 12 h during the light and dark phases of the lighting schedule (intact dogs) and of 11 h during the light period (castrated dogs). In the intact dogs testosterone concentrations ranged from 0·4 to 6·0 ng/ml over the 24-h period. LH concentrations varied from 0·2 to 12·0 ng/ml. In all animals, LH peaks were clearly followed, after about 50 min, by corresponding testosterone peaks, but no diurnal rhythm could be established. LH concentrations in the castrated dogs were high (9·8 ± 2·7 (s.e.m.) ng/ml), and still showed an episodic pattern in spite of the undetectable plasma testosterone levels.
Search for other papers by L. M. Penfold in
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Search for other papers by H. D. M. Moore in
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A new method for the cryopreservation of mouse spermatozoa was developed using a modified egg-yolk TES–Tris diluent containing 0.1% sodium lauryl sulfate and 1.25% (v/v) glycerol (mouse sperm cryoprotectant, MSC). Epididymal spermatozoa collected from 10-week-old CBA males were frozen at a rate of 5°C min−1 to 4°C and 50°C min−1 to −70°C using a programmable cell freezer. A percentage of the spermatozoa (25%) regained motility after thawing. In vitro fertilization with frozen–thawed spermatozoa resulted in 50% of oocytes developing to the two-cell stage. These two-cell embryos were placed in the oviducts of pseudopregnant recipients (C57BL/CBA) and 16% developed to be viable fetuses, or in the oviducts of pregnant recipients (MF1) and 17% developed to live offspring.
Search for other papers by N. W. MOORE in
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Search for other papers by L. E. A. ROWSON in
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Search for other papers by R. V. SHORT in
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Summary.
During the breeding seasons 1957-58 and 1958-59, a total of 280 fertilized eggs collected from Suffolk and Welsh Mountain ewes, mated to rams of their own breeds, was transferred at rates of either two or five eggs per animal to the Fallopian tubes or uterine horns of eighty Suffolk recipient ewes. Half of the recipients had been pretreated with injections of 1500 i.u. PMS in order to induce superovulation. The survival and development of transferred eggs, however, was found to be unaffected either by superovulation or by the breed of eggs transferred.
Overall prenatal mortality was divided into two periods (I) up to 17 or 18 days and referred to throughout as embryonic mortality or loss, and (2) 17 or 18 days to term, referred to as foetal mortality or loss.
Two peaks of embryonic mortality were observed, one occurring before and the other after attachment of embryos to the endometrium. Embryonic death accounted for almost all the prenatal mortality and the majority of the loss occurred before attachment. Foetal mortality occurring later than the 17th or 18th day of pregnancy was negligible.
The proportion of recipients becoming pregnant was the same in the groups which received two eggs and the group which received five eggs, but the ovum-survival rate following the transfer of five eggs was significantly lower than that following the transfer of two eggs. However, those ewes which received five eggs and subsequently became pregnant had significantly more lambs at term and normal embryos at autopsy than those which received only two eggs.
Of all the eggs transferred to the uteri and tubes, 49% and 29%, respectively, developed into normal embryos or lambs. The smaller survival rate following tubal transfers was due to a higher rate of embryonic mortality.
Search for other papers by L. M. Baggott in
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Search for other papers by S. Davis-Butler in
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Search for other papers by H. D. M. Moore in
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Summary. A system of test-pairing was used to detect reproductive behaviour in the grey short-tailed opossum. This enabled timing and characterization of the development of pro-oestrous and oestrous behaviour, and facilitated collection of ovulated and unovulated oocytes. Oestrus was induced 8·5 days (n = 80, 95% confidence limits 7·56–9·21) after the introduction of a male. Timed examination of the ovaries by laparotomy indicated that ovulation occurred 14–16 h after the first onset of oestrous behaviour. The development of follicles was linked to pro-oestrous behaviour, and ovulation occurred in the absence of copulation. Vaginal exfoliative cytology indicated that pro-oestrous behaviour was associated with an increasing number of keratinized epithelial cells, and at the time of maximum receptivity to males, a heavy infiltration of polymorphonuclear leucocytes was seen. Oocytes were typically marsupial: large (approximately 250 μm in diameter), with a yolky vitellus and thin zona pellucida. An average of 6 oocytes were ovulated per ovary.
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Search for other papers by C. E. ADAMS in
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Search for other papers by L. E. A. ROWSON in
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Summary.
Single blastomeres of two-, four- or eight-cell rabbit eggs devoid of the zona pellucida, enclosed in their own zona, or injected into an evacuated host zona were transferred to the Fallopian tubes of recipient does.
No single blastomeres devoid of the zona survived, while 30%, 19% and 11% of those of two-, four- and eight-cell eggs enclosed in their own zona developed into normal viable young.
Thirty-three out of ninety-seven single blastomeres of four-cell eggs injected into host zonae showed limited development, undergoing one or more cleavages, during the first 2 days after transfer. However, none implanted or developed into 6-day blastocysts. Failure to survive may have been due to leucocytic invasion of the zona and subsequent destruction of the blastomeres.
The developmental potential of individual blastomeres is briefly discussed in relation to the production of identical offspring.
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Search for other papers by E. J. EISEN in
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Search for other papers by L. C. ULBERG in
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Summary.
Intra- and inter-line transfers of blastocysts were performed between two lines of mice selected for high (H6) and low (L6) body weight at 6 weeks of age. A greater percentage of L6 blastocysts survived to term than did H6 blastocysts (7·8%, P < 0·01) and more L6 recipients littered than did the H6 recipients (19·7%, P < 0·01). A greater percentage of the mice born to the L6 recipients was found alive at birth (8·5%, P < 0·05), as was a greater percentage of the young carried in the uteri of the opposite line (8·3%, P < 0·05).
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Search for other papers by L. G. Moore in
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Search for other papers by N. L. Hudson in
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Search for other papers by S. Lun in
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Search for other papers by K. P. McNatty in
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This study investigated the effects of short-term (20 days) ovariectomy, the effects of FSH assay (radioimmunoassay, receptor assay or in vitro bioassay) and of FecBB genotype on the characteristics of pituitary FSH from Booroola ewes. Pituitary extracts were obtained from ovariectomized homozygous carriers (BB) and non-carriers (++, n = 8 per genotype) and ovary-intact controls (n = 4 per genotype). The extracts (n = 4 per genotype per treatment) were subjected to agarose suspension electrophoresis and the eluates were assayed by the three FSH methods. There were significant effects of ovariectomy (P < 0.01) and assay system (P < 0.05) but not of genotype on the median charge of FSH isoforms. The mean ± sem migration rates for FSH in intact and ovariectomized ewes were 0.469 ± 0.006 and 0.439 ± 0.006 albumin mobility units, respectively (P < 0.01), indicating a shift to more basic isoforms after short-term ovariectomy. When the pituitary extracts were subjected to anion-exchange HPLC, there was a significant (P < 0.01) shift to more basic isoforms in the ovariectomized ewes as shown using agarose electrophoresis, and no gene effects were noted. When the pituitary extracts (n = 4–8 per group) were injected into mature female mice, there were no significant effects of ovariectomy or genotype on the circulating half-lifes of the pituitary FSH isoforms. These results indicate that after short-term ovariectomy, the increase in plasma FSH concentrations is accompanied by a shift in the median charge of pituitary FSH isoforms without any observable change in their metabolic clearance rates. Moreover, the FecBB gene has little effect on the median charge or half-life of pituitary FSH.
