Placental vascular corrosion cast studies: A comparison between ruminants and humans

Leiser, Rudolf; Krebs, Christiane; Ebert, Brigitte; Dantzer, V.

doi:10.1002/(sici)1097-0029(19970701/15)38:1/2<76::aid-jemt9>3.0.co;2-s

Cited by 89 publications

(23 citation statements)

References 17 publications

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“…The sheep has a polycotyledonary placenta with up to 100 cotyledons that vary in number and size between individuals [140,141]. In particular, the sheep was used to develop techniques for catheterization of the uterine and umbilical vessels.…”

Section: Laurasiatheriamentioning

confidence: 99%

“…Such techniques allow repeated sampling from nonanesthetized animals free of surgical stress in order to obtain data on fetomaternal exchange processes, placental gas exchange, and fetal oxygen supply, under in vivo conditions and experimental manipulations [68,71,138,139,142,143]. The oxygen consumption of the placenta as a highly metabolically active organ is between half and 80% of the total oxygen uptake by the gravid uterus, mainly used for oxidative phosphorylation of glucose [141][142][143]. Indeed, about 80% of the uteroplacental glucose uptake is consumed by the placenta and not transferred to the fetus [144].…”

Section: Laurasiatheriamentioning

confidence: 99%

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Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

Mess

2014

Advances in Biology

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Here a survey of placental evolution is conducted. Placentation is a key factor for the evolution of placental mammals that had evolved an astonishing diversity. As a temporary organ that does not allow easy access, it is still not well understood. The lack of data also is a restriction for better understanding of placental development, structure, and function in the human. Animal models are essential, because experimental access to the human placenta is naturally restricted. However, there is not a single ideal model that is entirely similar to humans. It is particularly important to establish other models than the mouse, which is characterised by a short gestation period and poorly developed neonates that may provide insights only for early human pregnancy. In conclusion, current evolutionary studies have contributed essentially to providing a pool of experimental models for recent and future approaches that may also meet the requirements of a long gestation period and advanced developmental status of the newborn in the human. Suitability and limitations of taxa as alternative animal models are discussed. However, further investigations especially in wildlife taxa should be conducted in order to learn more about the full evolutionary plasticity of the placenta system.

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Section: Laurasiatheriamentioning

confidence: 99%

Section: Laurasiatheriamentioning

confidence: 99%

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

Mess

2014

Advances in Biology

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“…The sheep placenta has numerous discrete attachment sites comprised of the fetal cotyledon and maternal caruncle, rather than the large discoid placenta that occurs in humans, yet the human placenta is structurally divided into cotyledons as well. Regardless, the villous tree of the sheep cotyledon is structurally similar to that of the human placenta, as both can be divided into stem, intermediate and terminal villi [20], and the fetal vessels within the villi are comprised of stem arteries and veins, intermediate arterioles and venules, and terminal capillaries in both species. By no means is the sheep placenta a perfect model for the human, but the similarity in fetal placenta vascular structure coupled with the relative maturity of the fetus at birth, and the ability to repetitively obtain both maternal and fetal blood samples from singleton pregnancies [10.11], allows the sheep to serve as a useful model of placental vascular development and placental nutrient exchange.…”

Section: Placental Developmentmentioning

confidence: 99%

The pregnant sheep as a model for human pregnancy

2008

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Successful outcome of human pregnancy not only impacts the quality of infant life and well-being, but considerable evidence now suggests that what happens during fetal development may well impact health and well-being into adulthood. Consequently, a thorough understanding of the developmental events that occur between conception and delivery is needed. For obvious ethical reasons, many of the questions remaining about the progression of human pregnancy can not be answered directly, necessitating the use of appropriate animal models. A variety of animal models exist for the study of both normal and compromised pregnancies, including laboratory rodents, non-human primates and domestic ruminants. While all of these animal models have merit, most suffer from the inability to repetitively sample from both the maternal and fetal side of the placenta, limiting their usefulness in the study of placental or fetal physiology under non-stressed in vivo conditions. No animal model truly recapitulates human pregnancy, yet the pregnant sheep has been used extensively to investigate maternal-fetal interactions. This is due in part to the ability to surgically place and maintain catheters in both the maternal and fetal vasculature, allowing repeated sampling from non-anesthetized pregnancies. Considerable insight has been gained on placental oxygen and nutrient transfer and utilization from use of pregnant sheep. These findings were often confirmed in human pregnancies once appropriate technologies became available. The purpose of this review is to provide an overview of human and sheep pregnancy, with emphasis placed on placental development and function as an organ of nutrient transfer.

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“…While placenta in sheep are divided into many discreet attachment sites or placentomes, within each placentome the villous tree is structurally similar to that which occurs in the human, as both can be divided into stem, intermediate and terminal villi (9,10). In our model, pregnant ewes are exposed to high ambient temperature starting on day 40 of a Ϸ147 d gestation, and remain in this environment for approximately 80 d, resulting in reductions of placental and fetal weights (12) of approximately 51% and 42%, respectively, near term (135 d gestational age; dGA).…”

mentioning

confidence: 99%

Placental Expression of Angiopoietin-1, Angiopoietin-2 and Tie-2 during Placental Development in an Ovine Model of Placental Insufficiency-Fetal Growth Restriction

et al. 2005

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Placental vascular corrosion cast studies: A comparison between ruminants and humans

Cited by 89 publications

References 17 publications

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

The pregnant sheep as a model for human pregnancy

Placental Expression of Angiopoietin-1, Angiopoietin-2 and Tie-2 during Placental Development in an Ovine Model of Placental Insufficiency-Fetal Growth Restriction

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