Proceedings: Progesterone and oestrogen requirements for the survival of embryos in the ovariectomized ewe

Nw, Moore; Bg, Miller

doi:10.1530/jrf.0.0460536

Cited by 11 publications

(4 citation statements)

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“…Hawk et al (1963) pointed out, however, that the results of the study do not rule out the possibility that imbalances of ovarian hormones could be involved in early embryonic mortality by acting at a time before ovariectomy was performed. Support for such a possibility has come from the studies of Miller & Moore (1976a, b) and Moore & Miller (1976). These workers ovariectomized ewes and treated them with various combinations of progester¬ one and oestradiol before and after embryo transfer.…”

Section: Environmental Factorsmentioning

confidence: 99%

A review of embryonic mortality in cattle

Ayalon¹

1978

Reproduction

270

113

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Embryonic mortality, strictly interpreted, should refer to fertility losses during the embryonic period, i.e. the period extending from conception to completion of the stage of differentiation which, in the cow, occurs at approximately 45 days (Committee on Reproductive Nomenclature, 1972). However, many authors have included under this term, fertilization failure, as well as death after fertilization. Since the present review was written for presentation within the framework of a symposium on reproductive efficiency in domestic animals, it was considered necessary to include data on fertilization rates, for a more complete picture of fertility losses.Many reviews have been written dealing with embryonic mortality in farm animals and those concerned with cattle include papers

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Section: Environmental Factorsmentioning

confidence: 99%

A review of embryonic mortality in cattle

Ayalon¹

1978

Reproduction

270

113

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“…embryo development to changes in the uterine environment, by also examining changes in RNA and protein metabolism within the genital tract. Portions of this study have been briefly described elsewhere (Moore 1975;Miller and Moore 1976;Moore and Miller 1976). 0·50 1·00 0·625 1·25 0'75 1·50 1·00 2·00 1·25 2·50 1·50 3·00 2·0 4·0 2·5 5·0 3·0 6·0 4·0 Mature parous Merino ewes were used in the study and they had been bilaterally ovariectomized at least 2 months prior to the commencement of the experiments.…”

Section: Introductionmentioning

confidence: 99%

Effects of Progesterone and Oestradiol on RNA and Protein Metabolism in the Genital Tract and on Survival of Embryos in the Ovariectomized Ewe

Miller¹,

Moore²

1976

Aust. Jnl. Of Bio. Sci.

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The hormonal regulation of metabolism in the genital tract and the development of embryos during early pregnancy in the ewe have been examined. Ovariectomized ewes received injections of main· tenance progesterone, oestrous oestradiol and priming progesterone according to schedules designed to simulate endogenous ovarian secretion during early pregnancy, around the time of oestrus and during the luteal phase of the oestrous cycle immediately preceding oestrus.The survival and development of embryos was dependent upon the dose of maintenance progesterone and the duration of treatment at the time of transfer, but changes in progesterone dose did not change endometrial protein or RNA metabolism on particular days. Both priming progesterone and oestrous oestradiol were required for normal embryo development. Priming progesterone and oestrous oestradiol each increased endometrial RNA/DNA ratios during early pregnancy. There were no interactions between priming progesterone and oestrous oestradiol, their effects being simply additive. Neither maintenance nor priming progesterone had any effect on protein and RNA metabolism in the oviduct. It is suggested that in the intact ewe oestrogen secreted at oestrus and progesterone secreted prior to oestrus play important roles in the establishment of a uterine environment suitable for the subsequent normal development of embryos.

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“…The sequential exposure to progesterone before estrus, increased estradiol concentrations at estrus, and sufficient progesterone concentrations in the subsequent estrous cycle are necessary to establish the appropriate uterine environment for conceptus survival Moore, 1976, 1983;Moore and Miller, 1976;Moore, 1985;Wilmut et al, 1986). Estradiol, during the preovulatory period, is believed to "program" the uterus in preparation for the conceptus by modifying cellular morphology, preparing secretory organelles, and regulating steroid receptor amounts and localization.…”

Section: Hormonal Requirements For Pregnancy Establishmentmentioning

confidence: 99%

“…Estradiol, during the preovulatory period, is believed to "program" the uterus in preparation for the conceptus by modifying cellular morphology, preparing secretory organelles, and regulating steroid receptor amounts and localization. Early experiments with ovariectomized ewes Moore and Miller, 1976) established the importance of adequate preovulatory estradiol for embryonic survival and uterine function. In steroid-treated ovariectomized ewes, when estradiol concentrations equivalent to those achieved at estrus were omitted, normal embryos were not recovered 21 d after synchronous embryo transfer .…”

Section: Hormonal Requirements For Pregnancy Establishmentmentioning

confidence: 99%

TRIENNIAL REPRODUCTION SYMPOSIUM: Deficiencies in the uterine environment and failure to support embryonic development1

Bridges

Day

Geary

et al. 2013

Journal of Animal Science

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Pregnancy failure in livestock can result from failure to fertilize the oocyte or embryonic loss during gestation. The focus of this review is on cattle and factors affecting and mechanisms related to uterine insufficiency for pregnancy. A variety of factors contribute to embryonic loss and it may be exacerbated in certain animals, such as high-producing lactating dairy cows, and in some cattle in which estrous synchronization and timed AI was performed, due to reduced concentrations of reproductive steroids. Recent research in beef cattle induced to ovulate immature follicles and in lactating dairy cows indicates that deficient uterine function is a major factor responsible for infertility in these animals. Failure to provide adequate concentrations of estradiol before ovulation results in prolonged effects on expression and localization of uterine genes and proteins that participate in regulating uterine functions during early gestation. Furthermore, progesterone concentrations during early gestation affect embryonic growth, interferon-tau production, and uterine function. Therefore, an inadequate uterine environment induced by insufficient steroid concentrations before and after ovulation could cause early embryonic death either by failing to provide an adequate uterine environment for recognition of embryo signaling, adhesion, and implantation or by failing to support appropriate embryonic growth, which could lead to decreased conceptus size and failed maternal recognition of pregnancy.

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Proceedings: Progesterone and oestrogen requirements for the survival of embryos in the ovariectomized ewe

Cited by 11 publications

References 0 publications

A review of embryonic mortality in cattle

A review of embryonic mortality in cattle

Effects of Progesterone and Oestradiol on RNA and Protein Metabolism in the Genital Tract and on Survival of Embryos in the Ovariectomized Ewe

TRIENNIAL REPRODUCTION SYMPOSIUM: Deficiencies in the uterine environment and failure to support embryonic development1

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