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PubMed2005

Fertility in South Australian commercial Merino flocks: relationships between reproductive traits and environmental cues.

High levels of reproductive loss have been reported in commercial Merino flocks (n=68) from the cereal/livestock and high rainfall zones in South Australia (Kleemann DO, Walker SK. Fertility in South Australian commercial Merino flocks: sources of reproductive wastage. Theriogenology 2005;63:2075-88). Relationships between reproductive traits (estrus, ovulation, fertility, fecundity, lamb survival) and environmental end points (liveweight, condition score, temperature at mating, chill index at lambing) are reported in this paper. They were analysed within season of mating (October to December; January to March) and age of ewe (maiden as 1.5-year-old, mature as older). Incidence of estrus was positively related (P<0.05) to condition score in the October to November interval. Return rate to service was positively (P<0.05) influenced and fertility was negatively (P<0.05) influenced by the number of days ambient temperatures were > or =32.0 degrees C during mating, indicating that high ambient temperatures may reduce embryo survival. Liveweight and, to a lesser extent, condition score, accounted for significant proportions of variation associated with ovulation rate (39.3 and 12.7%, respectively). Ovulations per 100 ewes increased by 1.8 per kg increase in liveweight over all flocks. Ovulatory response to liveweight increased (P<0.01) from the October to December to the January to March period of mating (1.5 versus 3.4 ovulations per kg, respectively). Overall, a flock's fertility and fecundity increased by 0.27 and 1.42% per kg increase in liveweight, respectively. Reproductive wastage from partial failure of multiple ovulations (PFMO) was positively related to liveweight (P<0.01) and ovulation rate (P<0.001). Survival of single lambs was positively and curvilinearly related to maternal liveweight and condition score measured in late pregnancy (P<0.05). Linear relationship of these variables for twin lamb survival was significant for condition score only. Single and twin lamb survival were also positively related to liveweight and condition score at mating (P<0.05). We concluded that nutritional cues have a major impact on reproductive traits in commercial Merino flocks in South Australia; it sets the potential number of lambs (ovulation rate) and influences survival of lambs as early as at mating. Indications are that high ambient temperatures may influence embryo survival. It is recommended that future research efforts focus on: (a) prenatal nutritional influences on the physiology of mother-offspring behaviours at birth; and (b) possible peri-conceptional dietary factors controlling embryo loss resulting from partial failure of twin ovulations, to improve reproductive efficiency in the Merino.

Animals↗
PubMed2002

Amino acid turnover by elongating cattle blastocysts recovered on days 14-16 after insemination.

Blastocyst elongation from day 14 to day 16 after insemination coincides with a major phase of embryo loss in cattle. Protein synthesis, reflected in protein content, increases markedly over this period but little is known about the amino acid requirement of elongating blastocysts at this time. Cattle blastocysts produced in vivo were recovered on days 14-16 after insemination and cultured individually for up to 8 h in synthetic oviduct fluid containing a physiological mixture of amino acids plus 1 mmol glutamine l(-1) and 0.1% (w/v) polyvinyl alcohol (SOFaaPVA). After 1, 4 and 8 h in culture, an aliquot of culture medium was removed and the rate of amino acid depletion or production was calculated per unit of protein and per hour of culture. Amino acids were depleted or produced at different rates. Arginine was depleted from the medium at a significant rate (P < 0.05) during all culture periods. Alanine and glutamate were produced at a significant rate (P < 0.05) during all culture periods. The rate of alanine production was significantly greater (P < 0.05) in blastocysts recovered on day 14 compared with days 15 or 16 after insemination. Alanine production and arginine depletion tended to be greater in smaller embryos recovered on day 14 compared with larger and later stage embryos, indicating that earlier stage embryos may have higher metabolic activity than later stage embryos. Qualitatively, the pattern of amino acid consumption and production during elongation was similar to that shown from the zygote to early blastocyst stage.

Alanine↗
PubMed1992

Manipulation of reproduction in sheep.

Active immunization of cyclic ewes against androstenedione (using melatonin, Fecundin) has been shown to increase reproductive output by about 30 extra lambs per 100 ewes put to the ram in UK sheep flocks. However, this technique has not been widely adopted within the industry. One possible reason for this is that it results in an unacceptable incidence of triplet births, even though the litter size distribution is similar to that obtained for untreated flocks with the same overall mean lambing percentage. The use of progestagen sponges plus pregnant mares' serum gonadotrophin (PMSG) for the induction of out-of-season breeding in ewes is associated with a number of recognized shortcomings. A possible reason for the variability in conception rates is the high incidence of complete embryo loss or fertilization failure in ewes that are induced to superovulate after treatment with the doses of PMSG required to promote a high oestrous response. Recent studies have indicated that slow release implants of melatonin (Regulin) can advance the onset of the breeding season of commercial sheep flocks, but only by about 4 weeks. This means that the optimum treatment window varies according to the natural breeding season characteristics for the breed. Nevertheless, this treatment appears to overcome a number of the shortcomings of progestagen sponges plus PMSG. It also produces a modest increase in litter size per ewe pregnant (about 15 extra lambs per 100 ewes) without the wide variation in birth types and birth weights associated with PMSG. The development of a laparoscopic procedure that improves conception rates after intrauterine insemination of frozen semen allows comparisons of genetic merit across flocks. This should promote far greater rates of genetic improvement for traits of high economic importance than those achieved by within-flock selection and in the last two years has allowed the development of sire-referencing schemes within the major terminal sire breeds. Laparoscopic procedures for the collection and transfer of embryos in sheep now have the potential to overcome many of the limitations of more invasive surgical approaches, although the unpredictability of superovulatory responses remains a particular obstacle to full exploitation of multiple ovulation embryo transfer (MOET) for genetic improvement through the female line.

Animals↗
PubMed2003

Reduced SOD activity and increased neural tube defects in embryos of the sensitive but not of the resistant Cohen diabetic rats cultured under diabetic conditions.

BACKGROUND: The role of reactive oxygen species in the etiology of diabetes-induced anomalies was studied in a genetic model of nutritionally induced Type 2 diabetes mellitus: the Cohen diabetic sensitive (CDs) and resistant (CDr) rats. We have previously shown in this model that embryopathy may be induced by a combination of genetic and environmental factors. In our study we investigated the role of the antioxidant defense mechanism, genetic predisposition or environmental factors in embryos cultured under diabetic conditions. METHODS: CDs, CDr and Sabra rat 11.5-day old embryos were studied after 28 hr of culture in control (low glucose), high glucose, diabetic sub-teratogenic, and diabetic teratogenic media. Embryos were monitored for growth retardation and congenital anomalies. Activity of superoxide dismutase (SOD) and catalase-like (CAT) enzymes was measured in embryonic homogenates. RESULTS: In control medium, CDs embryos were significantly underdeveloped but exhibited no anomalies and SOD activity was not significantly different from that of CDr embryos. In high glucose medium, CDs embryos were smaller than CDr and Sabra embryos and smaller than CDs embryos cultured in control medium. Neural tube defects (NTD) were found predominantly in the CDs embryos starting from 14% in the high glucose medium and increasing to 29% in the sub-teratogenic medium. In the teratogenic medium, < 50% of the CDs and Sabra embryos were alive whereas all (100%) of the CDr embryos were alive. SOD activity significantly increased in CDs embryos when cultured in the high glucose medium but was significantly reduced in the sub-teratogenic medium. SOD activity was increased significantly in the Sabra embryos cultured in the sub-teratogenic medium but did not change in CDr embryos cultured in either one of the different culture media. CAT activity did not show any significant trend in either one of the rat strains or in any of the different culture conditions. CONCLUSIONS: Our results suggest that genetic susceptibility plays an important role in inducing underdevelopment and NTD in cultured CDs embryos in sub-teratogenic medium and in protecting the CDr embryos under the same conditions. The combination of a sub-teratogenic environment with genetic susceptibility is sufficient to reduce the activity of SOD, hence decreasing the ability of the CDs embryos to cope with diabetic sub-teratogenic environment and prevent NTD.

3-Hydroxybutyric Acid↗
PubMed2004

Developmental toxicity of artesunate and an artesunate combination in the rat and rabbit.

The artemisinins are playing an increasingly important role in treating multidrug-resistant malaria. The artemisinin, artesunate, is currently in use in Southeast Asia and is advocated for use in Africa. In these areas, more than one million people die of malaria each year, with the highest mortality occurring in children and pregnant women. To test the developmental toxicity in ICH-compliant animal studies, embryofetal development studies were conducted in rats and rabbits treated with artesunate alone or a three-drug combination (CDA) consisting of chlorproguanil hydrochloride, Dapsone, and artesunate in the ratio 1.00:1.25:2.00. Developmental toxicity seen with CDA could be attributed to the administered dose of artesunate. The hallmark effect of artesunate exposure was a dramatic induction of embryo loss, apparent as abortions in rabbits and resorptions in both rats and rabbits. In addition, low incidences of cardiovascular malformations and a syndrome of skeletal defects were induced at or close to embryolethal doses of artesunate in both rats and rabbits. The cardiovascular malformations consisted of ventricular septal and vessel defects. The skeletal syndrome consisted of shortened and/or bent long bones and scapulae, misshapen ribs, cleft sternebrae, and incompletely ossified pelvic bones. These developmental effects were observed largely in the absence of any apparent maternal toxicity. The no or low adverse effect levels were in the range of 5 to 7 mg/kg/day artesunate. Encouragingly, no adverse drug-related developmental effects have been observed in a limited number of pregnant women (more than 100 first trimester and 600 second and third trimester) treated with artemisinins, primarily artesunate. Investigations of the mechanism of developmental toxicity are ongoing to attempt to determine whether rats and rabbits are more sensitive to artemisinins than humans.

Abnormalities, Drug-Induced↗
PubMed2006

Mouse ZIP1 and ZIP3 genes together are essential for adaptation to dietary zinc deficiency during pregnancy.

Subfamily II of the solute-linked carrier 39A superfamily contains three well-conserved zinc transporters (ZIPs1, 2, 3) whose physiological functions are unknown. We generated mice homozygous for knockout alleles of ZIP1 and both ZIP1 and ZIP 3 (double-knockout). These mice were apparently normal when dietary zinc was replete, but when dietary zinc was limited during pregnancy embryos from ZIP1 or ZIP3 knockout mice were two to three times more likely to develop abnormally than those in wildtype mice, and 91% (71/78) of embryos developed abnormally in ZIP1, ZIP3 double-knockout mice. Analysis of the patterns of expression of these genes in mice revealed predominate expression in intestinal stromal cells, nephric-tubular epithelial cells, pancreatic ductal epithelial cells, and hepatocytes surrounding the central vein. This suggests that these zinc transporters function, at least in part, in the redistribution and/or retention of zinc rather than its acquisition from the diet. In conclusion, mutations in the ZIP1 and ZIP3 zinc transporter genes are silent when dietary intake of zinc is normal, but can dramatically compromise the success of pregnancy when dietary intake of zinc is limiting.

Adaptation, Physiological↗
PubMed1990

Early detection of pathologic pregnancy by transvaginal sonography.

Vaginal ultrasonography, by virtue of its excellent resolution, has resulted in changing our concepts about early pregnancy both in normal and abnormal gestations. The purpose of this report is to examine the clinical application of this technique in abnormal early pregnancy. Pathologic pregnancy ultimately will prove to be either (1) an ectopic pregnancy or (2) an intrauterine gestation that may be destined to failure. (A third group, fetuses with anomalies, will be dealt with elsewhere). Vaginal sonography has enhanced very early pathologic diagnosis in pregnancy because of its ability to image things previously not seen with such clarity, and because the scanning process can be carried out at the time of pelvic examination when the clinical indication is first encountered.

Abortion, Missed↗
PubMed1983

Interspecific hybrids and chimeras in mice.

Interspecific hybrids and chimeras in mammals provide unique tools for investigating problems in genetics and embryology, because of the degree of disparity between the two component genotypes. We have attempted to produce hybrids and chimeras between Mus musculus, the laboratory mouse, and Mus caroli, a wild species of mouse from Southeast Asia. M. musculus and M. caroli do not normally interbreed, although sterile hybrids can be produced at a low rate by artificial insemination. Extrinsic problems of genotypic incompatibility between the fetus and the maternal environment seem to be involved in poor hybrid survival, since M. caroli blastocysts also die when transferred to the M. musculus uterus. Death is associated with the generation of maternal T-cells which are cytotoxic to M. caroli target cells in vitro. It is not yet clear whether this immune response is the primary cause of death or is secondary to breakdown of some other components of the fetal-maternal interaction. It is clear, however, that it is the trophoblast layer that mediates survival or death of the foreign embryonic cells in the M. musculus juterus, since M. caroli inner cell mass cells can survive to term after injection into M. musculus blastocysts: Viable interspecific chimeras result. Even more convincing evidence is provided by the production of viable M. caroli offspring by trophoblast vesicle reconstitution using trophoblast of M. musculus genotype and inner-cell mass of M. caroli type. Studies of properties of isolated trophoblast tissues have indicated that M. caroli trophoblast may differ from M. musculus in both its antigenic and immunosuppressive properties. Elucidation of trophoblast-uterine interactions in these various interspecific pregnancies is being aided by the development of an in situ marker system, which can distinguish cells of the two species in sectioned material by in situ hybridization with a M. musculus satellite DNA probe. This same marker is also proving a very powerful tool for analyzing cell lineage development in chimeras.

Animals↗
PubMed2003

A study of the nature of embryonic lethality in LIS1-/- mice.

Homozygous deletion of the Lis1 gene (Lis1(-/-)) in mouse resulted in early embryonic lethality immediately after embryo implantation by an undefined mechanism. We seek to define the nature of this demise. LIS1 (pafah1b1) is a 46 kDa protein with seven tryptophan-aspartate (WD) repeats. It docks with many proteins and has been implicated in microtubular function, cell division, intercellular transport, and nuclear and cellular motility. Combined Western and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analyses showed that LIS1 expression from the blastocyst stage required new transcription from the embryonic genome. Consequently, the death of post-implantation embryos may not reflect the first time during development that LIS1 was required, rather, it may reflect the first time following depletion of gametic stores that its actions were essential. Following culture of blastocysts in vitro for 96 hr the inner cell mass (ICM) of null embryos were significantly smaller than ICM of wild-type siblings. Normal blastocyst outgrowths after 96-hr culture had high levels of LIS1 expression in the outer cells of developing ICM and extensive expression in trophoblast cells. Lis1(-/-) embryos had significantly smaller trophoblast nuclei than wild-type embryos. The results show that LIS1 expression is required for the continued normal development of the ICM and optimal trophoblast giant cell formation.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1988

Cleavage characteristics of mouse embryos inseminated and cultured after zona pellucida drilling.

The effects of zona drilling on mouse embryo development in vitro were evaluated. Following insemination, sperm were immediately concentrated at the area of drilling, and in zona-drilled eggs, pronuclei appeared 30-50 min earlier than in zona-intact controls. Zona-drilled oocytes fertilized at significantly higher rates than undrilled controls and, consequently, a greater percentage of eggs inseminated after zona drilling reached the blastocyst stage. The attrition rates of zona-drilled embryos at each cleavage stage did not differ significantly from controls. Manipulated embryos exhibited unique cleavage patterns. Some embryos lost their zonae entirely, whereas others became partially extruded at early cleavage stages. These anomalies led to separation of blastomeres from the zygote proper, aggregation of embryos to form giant composite morulae and blastocysts, and occasionally to formation of miniature twin blastocysts. These characteristics of cleavage indicate that although zona drilling of a cohort of oocytes is likely to lead to an increased number of live births relative to controls, some developmental abnormalities can be encountered, and these may be associated with embryo loss, spontaneous chimerism, or possibly with conception of monozygotic twins.

Animals↗
PubMed2002

Accumulation of cytoplasmic lipid droplets in bovine embryos and cryotolerance of embryos developed in different culture systems using serum-free or serum-containing media.

In this study, the quantitative fluctuation of cytoplasmic lipid droplets (LD) and cryotolerance were investigated in bovine embryos derived from in vitro-matured (IVM) and in vitro-fertilized (IVF) oocytes developed in different culture systems using serum-free or serum-containing media. The serum-free cultures were grown using IVMD101 medium in conjunction with bovine cumulus/granulosa cell (BCGC) cocultures or IVD101 medium without BCGC cocultures, and the serum-containing cultures were grown in the presence of BCGC cocultures using HPM199 medium supplemented with 5% calf serum (HPM199 + CS). Large numbers of sudanophilic LD were present in the cytoplasm of bovine embryos from 2-cell to hatched blastocyst stages, and the number and size differed between the embryos cultured in serum-free and serum-supplemented media. In the embryos cultured in HPM199 + CS, large (2-6 microm in diameter) sudanophilic LD increased significantly from the morula to the blastocyst stages. Throughout the embryonic development, the embryos developed in serum-free cultures with and without BCGC cocultures had numerous sudanophilic LD, but most of these droplets were small (<2 microm in diameter) and large LD were less numerous than those embryos cultured in HPM199 + CS. Giant LD (>6 microm in diameter) were frequently observed in morulae and blastocysts (including early blastocysts) developed in HPM199 + CS. Electron microscopic observations demonstrated that large LD were abundant in the cytoplasm of trophoblast and embryonic (inner cell mass) cells of blastocysts cultured in HPM199 + CS. These large LD were identified as osmophilic LD, an indication that these lipid inclusions contained a significant proportion of unsaturated lipids. Many elongated mitochondria were found in embryos developed in IVMD101 and IVD101 at the morula and early blastocyst stages, whereas many of the mitochondria in the morulae developed in HPM199 + CS were of an immature form such as spherical or ovoid shape. The survival and hatching rates of embryos (morulae, early blastocysts, and blastocysts) produced in serum-free media (both IVMD101 and IVD101) after post-thaw culture were superior to those of embryos produced in serum-containing medium. These results showed that bovine embryos cultured in serum-containing medium abnormally accumulated cytoplasmic lipids into their cytoplasm and the excess accumulation of cytoplasmic LD in embryos may affect the cryotolerance of embryos.

Animals↗
PubMed2001

Embryolethality induced by metronidazole (MTZ) in Rattus norvegicus.

Parasitic illnesses is increasing all over the world, especially in developing countries, and metronidazole (MTZ) is the therapeutic agent usually administered to children as well as adults at the reproductive age. In this work, we propose an evaluation of MTZ in order to analyze the potential reproductive damage in females by using Rattus norvegicus (Sprague-Dawley) as an animal model. Adult female rats were mated after MTZ treatments, and they were sacrificed at 21 days of gestation. Different types of damage were evaluated by using mortality, phenotypic abnormalities and reproductive capacity as parameters, and were studied and scored in 70 adult specimens (450 g/bw). They were divided into five groups: a) untreated females as a control group; females treated with b) DMSO as a solvent control group or c) 500 mg/kg/bw of MTZ per day for 7 days as therapeutic dose (TD); d) a half therapeutic dose (HD); and e) a double therapeutic dose (DD). Pre-implantation death in MTZ-treated groups was not significantly different from controls. However, drug treatments significantly increased the frequency of post-implantation deaths and the dominant lethals were ranged between 12.0 % and 17.8 %.

Animals↗
PubMed1975

The embryotoxicity of ytterbium chloride in golden hamsters.

Two experiments were performed to assess the embryotoxicity of intravenously administered ytterbium chloride in golden hamsters: (1) 50, 75, 100, or 150 mg/kg ytterbium chloride were injected early on the 8th gestation day; (2) 100 mg/kg ytterbium chloride were administered at 4 different times during the critical period of organogenesis in this species (7th day, 4 PM; 8th day, 8 AM or 4 PM; 9th day, 8 AM). The pregnant females were killed on the 12th, 14th, or 15th gestation day and the frequency of resorptions was determined, and surviving offspring were studied for the presence of external and internal malformations as well as skeletal damage. Relatively few externally visible malformations and no significant internal malformations were produced. Damage to the skeletal system included fused and supernumerary ribs, and many different sites of poor ossification. Maximal susceptibility to these effects occurred on the 8th day.

Abnormalities, Drug-Induced↗
PubMed1977

The effect of intrauterine position on the radiosensitivity of rat embryos.

Rats were exposed to gamma rays or helium ions on one of days 4-9 of gestation. Embryonic survival was recorded as a function of intrauterine position at autopsy on day 20 of gestation. Embryos located at the ovarian and cervical ends of the uterus experienced higher rates of mortality than did their littermates located at the middle of the uterine horn. This effect was observed in litters exposed to both radiation modalities on all days studied. The influence of intrauterine position on embryonic survival was directly proportional to radiation dose and to the number of fetuses occupying the uterus horn. Under the least advantageous conditions (i.e., a crowded uterine horn exposed to a moderately high radiation dose), the cervical embryo's probability of survival was less than half that of the litter as a whole. A disproportionately high rate of embryonic mortality at the cervical position was also observed in litters irradiated under hypoxic conditions, suggesting that the non-random distribution of radiation effect was not the result of variations in oxygen concentration within the uterus. In contrast, there was no indication that intrauterine position influenced the distribution of gross morphologic abnormalities in irradiated litters.

Animals↗
PubMed1983

An in vivo/in vitro evaluation of the teratogenic action of excess vitamin A.

Pregnant rats of CFHB strain were injected 81/2 days postcoitum with a 1% suspension of retinoic acid (RA) in arachis oil to give 20 mg RA per kg body weight. Control rats were injected with arachis oil only. After 26 hours, one uterine horn was removed from each rat and the embryos cultured in serum from untreated rats. The embryos in the other horn were allowed to continue development in vivo. After a further 48 hours the cultures were terminated and the second uterine horn removed from each rat. This provided four groups of embryos for comparison: (1) embryos from RA-treated rats, (2) cultured embryos from RA-treated rats, (3) embryos from control rats, and (4) cultured embryos from control rats. The results showed that the effects of the teratogen on the cultured embryos were similar to those on the embryos allowed to continue development for the same period in the mother. In both groups RA reduced protein synthesis, inhibited somite and limb bud formation, and caused various neural tube defects, particularly microcephaly and abnormalities in the closure of the anterior and posterior neuropores.

Abnormalities, Drug-Induced↗
PubMed1983

Retained developmental capacity of blastocysts transferred from lead-intoxicated mice.

Blastocysts from mice injected with an implantation-inhibiting dose of lead were transferred nonsurgically to pregnant foster mothers. This was done to obtain information about the ability of these blastocysts to implant and to develop into late fetal stages. There was no difference in the ability of lead-treated blastocysts to implant as compared with the transferred nontreated blastocysts. Nor was there any effect of the exposure to lead before implantation upon the development of the blastocysts into normal fetuses. The results indicate that the preimplantation blastocysts are protected from possible harmful influences from the lead treatment of the mothers, and that the implantation failure in lead-treated mice is not due to the inability of the blastocysts to implant. A significant increase in the frequency of exencephaly was observed in fetuses derived from transplanted blastocysts as compared with those from normal pregnant mice.

Abnormalities, Drug-Induced↗