Uterine Blood Flow during Early Pregnancy in Ewes: Interaction between the Conceptus and the Ovary Bearing the Corpus Luteum

Reynolds, Lawrence P.; Magness, Ronald R.; Ford, Stephen P.

doi:10.2527/jas1984.582423x

Cited by 49 publications

(17 citation statements)

References 21 publications

(28 reference statements)

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“…vascular growth and expression of angiogenic and other factors) in the maternal placenta. The patterns of changes in vascular development parallel those for the expression of several angiogenic and other factors indicating complex regulation of angiogenic processes which regulate uterine and placental blood flow (Reynolds et al 1984, Reynolds & Redmer 1995. Thus, angiogenesis is crucial in developing and building the placental life line between the maternal and fetal systems, and when affected, fetal growth and development are also affected (Carter & Charnock-Jones 2001, Wulff et al 2003, Arroyo & Winn 2008, Fraser & Duncan 2009.…”

Section: Discussionmentioning

confidence: 96%

Placental development during early pregnancy in sheep: vascular growth and expression of angiogenic factors in maternal placenta

Grazul-Bilska¹,

Borowicz²,

Johnson³

et al. 2010

Reproduction

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Placental vascular development (angiogenesis) is critical for placental function and thus for normal embryonic/fetal growth and development. Specific environmental factors or use of assisted reproductive techniques may result in poor placental angiogenesis, which may contribute to embryonic losses and/or fetal growth retardation. Uterine tissues were collected on days 14, 16, 18, 20, 22, 24, 26, 28, and 30 after mating and on day 10 after estrus (nonpregnant controls) to determine vascular development and expression of several factors involved in the regulation of angiogenesis in the endometrium. Compared with controls, several measurements of endometrial vascularity increased (P!0.001) including vascular labeling index (LI; proportion of proliferating cells), the tissue area occupied by capillaries, area per capillary (capillary size), total capillary circumference per unit of tissue area, and expression of factor VIII (marker of endothelial cells), but capillary number decreased (P!0.001). Compared with controls, mRNA for placental growth factor, vascular endothelial growth factor receptors, angiopoietins (ANGPT) 1 and 2, ANGPT receptor TEK, endothelial nitric oxide synthase, and hypoxia-inducible factor 1a increased (P!0.05) during early pregnancy. Vascular LI was positively correlated (P!0.05) with several measurements of vascularity and with mRNA expression of angiogenic factors. These data indicate that endometrial angiogenesis, manifested by increased vascularity and increased expression of several factors involved in the regulation of angiogenesis, is initiated very early in pregnancy. This more complete description of early placental angiogenesis may provide the foundation for determining whether placental vascular development is altered in compromised pregnancies.

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Section: Discussionmentioning

confidence: 96%

Placental development during early pregnancy in sheep: vascular growth and expression of angiogenic factors in maternal placenta

Grazul-Bilska¹,

Borowicz²,

Johnson³

et al. 2010

Reproduction

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“…Indeed, DAVID analysis identified blood circulation and circulatory system process as biological processes affected by day of pregnancy and early P4 treatment. Although angiogenesis has not been well studied during early pregnancy in ruminants, increases in uterine blood flow do occur during early pregnancy in sheep (68).…”

Section: Discussionmentioning

confidence: 99%

Discovery of candidate genes and pathways in the endometrium regulating ovine blastocyst growth and conceptus elongation

Satterfield

Song

Kochan

et al. 2009

Physiological Genomics

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Establishment of pregnancy in ruminants requires blastocyst growth to form an elongated conceptus that produces interferon tau, the pregnancy recognition signal, and initiates implantation. Blastocyst growth and development requires secretions from the uterine endometrium. An early increase in circulating concentrations of progesterone (P4) stimulates blastocyst growth and elongation in ruminants. This study utilized sheep as a model to identify candidate genes and regulatory networks in the endometrium that govern preimplantation blastocyst growth and development. Ewes were treated daily with either P4 or corn oil vehicle from day 1.5 after mating to either day 9 or day 12 of pregnancy when endometrium was obtained by hysterectomy. Microarray analyses revealed many differentially expressed genes in the endometria affected by day of pregnancy and early P4 treatment. In situ hybridization analyses revealed that many differentially expressed genes were expressed in a cell-specific manner within the endometrium. The Database for Annotation, Visualization, and Integrated Discovery (DAVID) was used to identify functional groups of genes and biological processes in the endometrium that are associated with growth and development of preimplantation blastocysts. Notably, biological processes affected by day of pregnancy and/or early P4 treatment included lipid biosynthesis and metabolism, angiogenesis, transport, extracellular space, defense and inflammatory response, proteolysis, amino acid transport and metabolism, and hormone metabolism. This transcriptomic data provides novel insights into the biology of endometrial function and preimplantation blastocyst growth and development in sheep.

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“…Placentation that occurs during early pregnancy is one of the most important developmental events (Boshier, 1969;King et al, 1982), since it is tightly associated with embryonic survival (Reynolds and Redmer, 2001). Extensive angiogenesis occurs in both the maternal uterus and fetal placenta during placentation, and umbilical blood flow increases during the same time (Reynolds et al, 1984;Reynolds and Redmer, 1992;. It has been reported that early embryonic mortality increases as placental vascular development decreases (Meegdes et al, 1988;Reynolds and Redmer, 1995).…”

Section: Nutrition Related To Fetal Growth During Late Gestationmentioning

confidence: 99%

Within-litter variation in birth weight: impact of nutritional status in the sow

Yuan

Zhu

Shi

et al. 2015

J. Zhejiang Univ. Sci. B

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Accompanying the beneficial improvement in litter size from genetic selection for high-prolificacy sows, within-litter variation in birth weight has increased with detrimental effects on post-natal growth and survival due to an increase in the proportion of piglets with low birth-weight. Causes of within-litter variation in birth weight include breed characteristics that affect uterine space, ovulation rate, degree of maturation of oocytes, duration of time required for ovulation, interval between ovulation and fertilization, uterine capacity for implantation and placentation, size and efficiency of placental transport of nutrients, communication between conceptus/fetus and maternal systems, as well as nutritional status and environmental influences during gestation. Because these factors contribute to within-litter variation in birth weight, nutritional status of the sow to improve fetal-placental development must focus on the following three important stages in the reproductive cycle: pre-mating or weaning to estrus, early gestation and late gestation. The goal is to increase the homogeneity of development of oocytes and conceptuses, decrease variations in conceptus development during implantation and placentation, and improve birth weights of newborn piglets. Though some progress has been made in nutritional regulation of within-litter variation in the birth weight of piglets, additional studies, with a focus on and insights into molecular mechanisms of reproductive physiology from the aspects of maternal growth and offspring development, as well as their regulation by nutrients provided to the sow, are urgently needed.

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Uterine Blood Flow during Early Pregnancy in Ewes: Interaction between the Conceptus and the Ovary Bearing the Corpus Luteum

Cited by 49 publications

References 21 publications

Placental development during early pregnancy in sheep: vascular growth and expression of angiogenic factors in maternal placenta

Placental development during early pregnancy in sheep: vascular growth and expression of angiogenic factors in maternal placenta

Discovery of candidate genes and pathways in the endometrium regulating ovine blastocyst growth and conceptus elongation

Within-litter variation in birth weight: impact of nutritional status in the sow

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