Placental Structure (placental + structure)

Distribution by Scientific Domains

Selected Abstracts

The influence of mating system on the intensity of parent,offspring conflict in primates

Abstract An evolutionary conflict of interest exists between parents and their offspring over the partitioning of parental investment (PI) among siblings. When the direct fitness benefits to offspring of increased PI, outweigh the inclusive fitness costs from lost future sibling fitness, selection should favour the evolution of offspring selfishness over altruism. In theory, this conflict is heightened when females are not strictly monogamous, as current offspring should be less altruistic towards future half-siblings than they would be towards full-siblings. Using data collected on foetal growth rate (representing prenatal PI) in primates, I test the prediction from theory that the resolution of the parent-offspring conflict will be closer to the offspring's evolutionary optima in polyandrous species than in more monandrous species. Using phylogenetic comparative analysis, and controlling for allometry, I show that offspring are able to obtain more PI when the probability of future full-siblings decreases, and that this is most pronounced in taxa where there is the opportunity for direct foetal access to the maternal bloodstream. These results support the hypothesis that the resolution of prenatal PI conflict is influenced by both a species' mating system and by its placental structure. [source]

Fetal signaling through placental structure and endocrine function: Illustrations and implications from a nonhuman primate model

Julienne N. Rutherford
The placenta is a transmitter of fetal need and fetal quality, interfacing directly with maternal physiology and ecology. Plasticity of placental structure and function across the developmental timeframe of gestation may serve as an important tool by which a fetus calibrates its growth to shifting maternal ecology and resource availability, and thereby signals its quality and adaptability to a changing environment. Signals of this quality may be conveyed by the size of the placental interface, an important marker of fetal access to maternal resources, or by production of placental insulin-like growth factor-II, a driver of fetoplacental growth. Litter size variation in the common marmoset monkey offers the opportunity to explore intrauterine resource allocation and placental plasticity in an important nonhuman primate model. Triplet marmosets are born at lower birth weights and have poorer postnatal outcomes and survivorship than do twins; triplet placentas differ in placental efficiency, microscopic morphology, and endocrine function. Through placental plasticity, triplet fetuses are able to adjust functional access to maternal resources in a way that allows pregnancy to proceed. However, the costs of such mechanisms may relate to reduced fetal growth and altered postnatal outcomes, with the potential to lead to adverse adult health consequences, suggesting an important link between the placenta itself and the developmental origins of health and disease. Am. J. Hum. Biol. 2009. 2009 Wiley-Liss, Inc. [source]

First-trimester assessment of placenta function and the prediction of preeclampsia and intrauterine growth restriction

Yan Zhong
Abstract Preeclampsia and intrauterine growth restriction (IUGR) are major contributors to perinatal mortality and morbidity worldwide. Both are characterized by impaired trophoblastic invasion of the maternal spiral arteries and their conversion from narrow muscular vessels to wide non-muscular channels. Despite improvement in the understanding of the pathophysiology of these conditions, ability to accurately identify pregnant woman who will develop them is limited. This greatly impairs the development and testing of preventive interventions. While different measures of placental dysfunction have been associated with increased risk for adverse pregnancy outcomes, the ability of any single one to accurately predict these outcomes is poor. Developing predictive tests is further challenged by difficulty in the timing of the measurements, as both the structural and biochemical characteristics of the placenta change with increasing gestational age. The ideal screening test would accurately predict the development of adverse pregnancy outcomes early enough to provide a window for preventive interventions. Improvement in ultrasound technology provides potentially useful novel tools for evaluating placental structure, but measuresments need to be standardized in order to be useful. Maternal serum analyte screening is a noninvasive test of placental biochemical function, but present serum marker alone is not sufficiently accurate to suggest its routine use in clinical practice. The use of first trimester biochemical markers in combination with uterine artery Doppler screening is promising as a potential screening tool. Prospective longitudinal studies using standardized methodology are necessary to further evaluate the choice of parameters and strategies of combination to achieve the best predictive models. Copyright 2010 John Wiley & Sons, Ltd. [source]

Transfer of maternally administered fusogenic liposome-DNA complexes into monkey fetuses in a pregnancy model

Makoto Hirano
Abstract Background Materno-fetal transfer of intravenously administered liposome-plasmid DNA complexes has been demonstrated only in mice. Studies on its materno-fetal transfer in the pregnant monkey model is needed because of critical differences in placental structure between primates including humans and rodents. Methods The reporter plasmid pEGFP-C1 was formulated in cationic lipid containing polybrene and vesicular stomatitis virus G protein. The fusogenic liposome-plasmid DNA complexes were intradermally injected into pregnant common marmosets (N=2), a New World monkey, near term. DNA extracted from fetal tissues was subjected to PCR for detection of the egfp gene. Confocal microscopy and immunostaining were performed to determine the sites of transgene expression in the fetal organs. Results The egfp gene was detected in fetal blood and major organs (heart, liver, lung). The encoded protein was mainly produced in the endothelial cells of blood vessels in the fetal lungs. Conclusions This is the first report on materno-fetal transfer of intradermally administered fusogenic liposome-plasmid DNA complexes and fetal expression of a transgene in primates. Copyright 2002 John Wiley & Sons, Ltd. [source]

REVIEW ARTICLE: Immunological Paradigms and the Pathogenesis of Ovine Chlamydial Abortion

Gary Entrican
Citation Entrican G, Wattegedera S, Wheelhouse N, Allan A, Rocchi M. Immunological paradigms and the pathogenesis of ovine chlamydial abortion. Am J Reprod Immunol 2010 Successful mammalian pregnancy involves complex immunological interactions between the mother and foetus that are not yet fully understood. A number of immunological paradigms have been established to explain the failure of the maternal immune system to reject the semi-allogeneic foetus, mainly based on studies in mice and humans. However, as placental structure, gestation periods and number of concepti per pregnancy can vary greatly between mammals, it is not always clear how applicable these immunological paradigms are to reproduction in other species. Here, we discuss the predictions of three important immunological paradigms in relation to the pathogenesis of ovine enzootic abortion (OEA), a common cause of infectious abortion in sheep and other ruminants. OEA is caused by the intracellular Gram-negative bacterium Chlamydophila abortus that exhibits a tropism for placental trophoblast. The paradigms of particular relevance to the pathogenesis of OEA are as follows: (i) intracellular bacterial infections are controlled by TH1-type CD4+ve T cells; (ii) indoleamine 2,3-dioxygenase is expressed in the placenta to prevent immunological rejection of the semi-allogeneic foetus; and (iii) pregnancy is a maternal TH2-type phenomenon. We discuss the relevance and validity of these paradigms for chlamydial abortion and reproductive immunology in sheep. [source]