Evidence of Nitric Oxide Impairment During Hypertensive Pregnancies.

Hypertensive disorders of pregnancy complicate up to 10% of pregnancies worldwide, and they can be classified into (1) gestational hypertension, (2) preeclampsia, (3) chronic hypertension and (4) chronic hypertension with preeclampsia. Nitric oxide (NO) plays an essential role in the haemodynamic adaptations observed during pregnancy. It has been shown that the nitric oxide pathway's dysfunction during pregnancy is associated with placental- and vascular-related diseases such as hypertensive disorders of pregnancy. This review aims to present a brief definition of hypertensive disorders of pregnancy and physiological maternal cardiovascular adaptations during pregnancy. We also detail how NO signalling is altered in the (a) systemic vasculature, (b) uterine artery/spiral arteries, (c) implantation and (d) placenta of hypertensive disorders during pregnancy. We conclude by summarizing the anti-hypertensive therapy of hypertensive disorders of pregnancy as a specific management strategy.

The Placental Function Beyond Pregnancy: Insights from Latin America.

Currently, more than 100,000 papers had been published studying the placenta in both physiological and pathological contexts. However, relevant health conditions affecting placental function, mostly found in low-income countries, should be evaluated deeper. This review will raise some - of what we think necessary - points of discussion regarding challenging topics not fully understood, including the paternal versus maternal contribution on placental genes imprinting, placenta-brain communication, and some environmental conditions affecting the placenta. The discussions are parts of an international effort to fulfil some gaps observed in this area, and Latin-American research groups currently evaluate that.

Impact of high-fat diet consumption during prolonged period of pregnancy on placenta structures and umbilical vascular growth in goats

This study aimed to verify the impact of high-fat diet consumption for a prolonged period on oxidative stress, fetal growth, umbilical vascular system, and placental structures in pregnant goats. Twenty-two pregnant goats were grouped into the control diet (n= 11) and fat diet (n = 11). Flaxseed meal was added to the fat diet, replacing the corn grain of concentrate, from gestational day 100 to delivery date. Diets were isonitrogenous and isoenergetic, differing in fat content (2.8% vs. 6.3% dry matter). The fat group showed higher feed intake and total plasma lipid levels than the control group (P < 0.001). No difference was found in placentome, and umbilical vascular development. Fat diet-fed goats exhibited a lower systolic peak in the umbilical artery. At delivery, placental traits were similar with the exception of the cotyledon width (P = 0.0075), which was smaller in the fat group and cotyledon surface (P = 0.0047) for multiple pregnancy of fat diet. Cotyledonary epithelium showed more intense staining of lipid droplets and a greater area for lipofuscin staining in the fat group compared to control group (P < 0.001). The mean live weight of the kids was lower in the fat group in the first week after delivery than in control group. Thus, in goats, the continuous administration of a high-fat diet during pregnancy does not appear to modify the fetal-maternal vascular structures but has an impact on a part of the placental structure; therefore, its use must be carefully evaluated.(AU)

Central role of the placenta during viral infection: Immuno-competences and miRNA defensive responses.

Pregnancy is a unique immunological condition in which an "immune-diplomatic" dialogue between trophoblasts and maternal immune cells is established to protect the fetus from rejection, to create a privileged environment in the uterus and to simultaneously be alert to any infectious challenge. The maternal-placental-fetal interface (MPFI) performs an essential role in this immunological defense. In this review, we will address the MPFI as an active immuno-mechanical barrier that protects against viral infections. We will describe the main viral infections affecting the placenta and trophoblasts and present their structure, mechanisms of immunocompetence and defensive responses to viral infections in pregnancy. In particular, we will analyze infection routes in the placenta and trophoblasts and the maternal-fetal outcomes in both. Finally, we will focus on the cellular targets of the antiviral microRNAs from the C19MC cluster, and their effects at both the intra- and extracellular level.

Pulsatility of the umbilical cord in full-term natural childbirths / Pulsatilidad del cable umbilical en nacimientos a plazo normal / Pulsatilidade do cordão umbilical em partos normais a termo

ABSTRACT Objective Measure umbilical cord pulsatility time and evaluate correlation/association with maternal and neonatal characteristics. Method Cross-sectional study, with 76 binomials, carried out in 2017, in a maternity hospital in Alagoas. Analysis with Pearson or Spearman correlation test and Mann-Whitney or Kruskal-Wallis test. Results Sixty-two parturients and their newborns participated of the research. The women had a gestational age ≥ 37 weeks, natural cephalic birth, without distortions. The newborns had average weight of 3326.29g, mostly male. The umbilical cord pulsatility time was 285.48s. There is a correlation between umbilical cord pulsatility time and placental delivery time (p<0.001). Other correlations/associations were not significant. Conclusion It suggested using a correlation between pulsatility time and placental delivery time in clinical decision making for good practices in childbirth assistance.

RESUMEN Objetivo Medir tiempo de pulsatilidad del cordón umbilical y evaluar la correlación/asociación con las características maternas y neonatales. Método Estudio transversal, con 76 pares, realizado en 2017, en maternidad en Alagoas. Análisis con la prueba de correlación de Pearson o Spearman y la prueba de Mann-Whitney o Kruskal-Wallis. Resultados Sesenta y dos mujeres en trabajo de parto y sus recién nacidos participaron. Las mujeres tenían edad gestacional ≥ 37 semanas, parto cefálico normal, sin distorsiones. Los recién nacidos tenían peso promedio de 3326.29g, la mayoría de ellos varones. Tiempo de pulsatilidad del cordón umbilical fue de 285.48s. Había correlación entre el tiempo de pulsatilidad del cordón umbilical y el momento del parto placentario (p<0,001). Otras correlaciones/asociaciones no fueron significativas. Conclusión Sugiere una correlación entre el tiempo de pulsatilidad y el tiempo de parto placentario para las buenas prácticas en la atención del parto.

RESUMO Objetivo Mensurar tempo de pulsatilidade do cordão umbilical e avaliar correlação/associação com característica maternas e neonatais. Método Estudo transversal, com 76 binômios, realizado no ano de 2017, em maternidade de Alagoas. Análise com teste de correlação de Pearson ou Spearman e teste de Mann-Whitney ou Kruskal-Wallis. Resultados Sessenta e duas parturientes e seus recém-nascidos participaram da pesquisa. As mulheres tinham idade gestacional ≥ 37 semanas, parto normal cefálico, sem distorcias. Os recém-nascidos tinham peso médio de 3326,29g, maioria do sexo masculino. O tempo de pulsatilidade do cordão umbilical foi 285,48s. Há correlação entre tempo de pulsatilidade do cordão umbilical e tempo de dequitação da placenta (p<0,001). Demais correlações/associações não foram significativas. Conclusão Sugere-se o uso correlação entre tempo de pulsatilidade e tempo de dequitação da placenta na tomada de decisão clínica para boas práticas na assistência ao parto.

Association of placental nutrient sensing pathways with birth weight.

Birth weight (BW) is an important indicator for newborn health. Both high and low BW is associated with increased risks for adult metabolic diseases. AMPK (AMP-activated protein kinase), mTOR (mechanistic target of rapamycin), and insulin/IGF1 (insulin-like growth factor 1) pathways may function as placental sensors of maternal hormonal and nutritional status. However, the physiological role of these pathways in placenta has not been completely elucidated. To evaluate expression and activation of AMPK, mTOR, and insulin/IGF1 pathways and its association with placental weight (PW), BW, and maternal hormonal and metabolic status, we performed a cross-sectional study in placentas from non-obese mothers with SGA (n = 17), AGA (n = 19) and LGA (n = 10) newborns. We analyzed placental expression of total and phosphorylated key proteins from the AMPK, mTOR and insulin/IGF1 pathways. Maternal and cord blood hormones were determined by ELISA. AMPK and LKB1 activation correlated negatively with PW and BW, cord leptin, and pregestational BMI. Placental SIRT1 inversely correlated with BW, cord leptin, neonatal HOMA-IR, and maternal IGF1. PGC1α correlated negatively with PW and BW. Phosphorylated mTOR positively correlated with maternal glucose, PW and BW. IGF1R was lower in SGA. No changes in p-IGF1R, INSRb, total AKT or p-AKT were found, and pPDK1 was lower in SGA and LGA. These results suggest that placental AMPK, insulin/IGF1, and mTOR pathways may influence fetal growth, perhaps regulating placental physiology, even in metabolically healthy pregnancies. Our study highlights these nutrient sensing pathways as potential molecular mechanisms modulating placental adaptations and, thus, long-term metabolic health.

Phenomenological and Thermodynamic Model of Gas Exchanges in the Placenta during Pregnancy: A Case Study of Intoxication of Carbon Monoxide.

The present work simulates the transport of oxygen, carbon dioxide, and carbon monoxide between a fetus's circulatory system and the mother's. The organ responsible for this exchange is the placenta. Carbon monoxide is a common air pollutant, and it impacts the physiological conditions even in low concentration. The impacts of carbon monoxide are especially dangerous for pregnant women, fetuses, and newborn babies. A model of carbon monoxide transport, from the literature, is modified to simulate a pregnant woman (original model was a male), therefore changing some parameters to express the adjusted respiratory system. It was considered the gas exchange in the placenta, to evaluate the concentration of these different gases in the fetus arterial and venous blood. Three methods of the exergy analysis are implemented for both mother and fetus respiratory systems, aiming at the comparison with the respiratory system of a male adult. The destroyed exergy of the literature did not have the same trend as the models proposed in this article, taking into consideration the hemoglobin reactions. In contrast, the entropy generation associated only with the diffusion transport phenomena was one order of magnitude lower than the other methods. The placenta destroyed exergy rate is significantly higher compared to the irreversibilities of the mother's respiratory system. One possible explanation is the fact that the placenta has other physiological functions than gas transportation.

Role of VEGF in the differential growth between the fetal and placental ends of the umbilical cord.

INTRODUCTION: The umbilical cord (UC) is a vital structure; its alterations affect the newborn and neurological impact can be permanent. Paradoxically, factors that determine it remain unknown. We explore the differential VEGF protein expression in the UC's proximal and distal portions in relation to the hypothesis that the UC has differential growth and that VEGF plays a role in it. METHODS: An observational analytical study was performed. One UC segment was taken proximal to fetus and another distal; both were randomly processed; VEGF immunohistochemical analysis was performed; two blinded pathologists read results. RESULTS: Forty-eight newborns were included. Protein expression between the two edges of the umbilical cord, in any kind of cells, was interpreted. Endothelium, amnion, and stromal cells expressed VEGF; the first two were not different between opposite ends. Stromal cells had differential expression: higher in the proximal to the fetus portion. CONCLUSION: Knowledge of molecular factors is necessary. UC cells widely expressed VEGF, possibly contributing to UC growth. Even though stromal cell expression was different, the interaction with activity close to the fetus must be explored.

Effect of prepubertal nutrition on cellular apoptosis and proliferation in at term placenta of Anglo-Nubian goats.

The aim of this study was to evaluate the effect of feed restriction with or without monensin supplementation, followed by a re-feeding period on cellular apoptosis and proliferation in at term placenta of Anglo-Nubian goats. To evaluate the induction of apoptosis through the intrinsic pathway, proteins Bax and Bcl-2 were determinated. The apoptosis was related with the cell proliferation indices through Ki67 determination. The treatments were applied for 250 days and were (a) ad libitum feeding (control; n = 5); (b) restricted feeding at 70% of control (restricted; n = 7); and (c) restricted with monensin supplementation (monensin; n = 7). After treatments, all the animals were fed to support their requirements. After parturition, 27 placentas were gathered. The placental cellular structure was studied by high-resolution light microscopy and transmission electron microscopy; the cellular proliferation was determined by Ki67 index, and Bax and Bcl-2 proteins were localized by immunohistochemical analysis. Differences in cell proliferation through the Ki67 index were found in monensin group placentas. Monensin supplementation stimulated the placental cell proliferation reversing the effect of feed restriction during the peripuberal period. A significant increase of Bcl-2 in placentas of restricted group was found, and it would provide a protective effect on the placental structure. A lack of the Bcl-2 protective effect was observed in control and monensin group placentas, probably meaning that the observed apoptosis would be induced through the intrinsic signalling pathway. A balance between apoptosis and cell proliferation is necessary to maintain tissue homoeostasis during caprine placental development.

Comparative Study of Prenatal Development Between Myotis albescens (Chiroptera: Vespertilionidae) and Eumops patagonicus (Chiroptera: Molossidae): The Chorionic Vesicle and Extraembryonic Membranes Considerations.

We presented a comparative study of two species of South American bats, Myotis albescens and Eumops patagonicus, about prenatal development. This study was carried out using 60 specimens, which were measured and photographed, and the embryonic stage was assigned by the staging system for Carollia perspicillata. We observed that the chorionic vesicle showed similarities in the disposition of the extraembryonic membranes, but they differed in characteristics of their yolk sac; in E. patagonicus, it was more glandular than M. albescens. M. albescens presented a well-developed discoid placenta with a caudal antimesometrial position, but E. patagonicus presented a diffuse placenta, which persists until the end of gestation and a discoid placenta in the uterus-tubal junction. In the embryogenesis, early stages, middle stages, and late stages were defined. In the early stage, the embryonic morphology is similar in the two species. The middle stage is characterized by the muzzle and pinna formation, fore and hind limb regionalization, and the formation of the patagium primordium. In the late stage, the overall growth of the embryo occurs. Its fore and hind limbs, patagium, and the typical craniofacial features are configured. We conclude that in early stages of development, the embryonic morphology of M. albescens and E. patagonicus is similar, while in late stages differences are evident; mainly the craniofacial structures and uropatagium configuration characteristics that allow their classification at the family level. Moreover, differences in time of fusion of maxillary and mandibular process were registered. This could be related to the morphology of the muzzle of each species. Anat Rec, 301:1527-1543, 2018. © 2018 Wiley Periodicals, Inc.

Susceptibility of placental mitochondria to oxidative stress.

BACKGROUND: Two different mitochondrial fractions (MFs) have been characterized in the human placenta: the "light" and "heavy" fractions (LMF and HMF). Although these organelles are the main source of reactive oxygen species, an imbalance between their production and the rate of detoxification represents a serious threat to mitochondrial homeostasis and, in the case of the placenta, also to the fetus. The aim of this study was to evaluate the antioxidant capacity and susceptibility to oxidative stress in both types of MFs. METHODS: Human MFs were isolated from healthy donors (n = 11) and either incubated or not with H2 O2 . Catalase (CAT) activity, and reduced glutathione (GSH), lipid peroxidation (LP), and protein carbonylation (PC) levels were determined. RESULTS: H2 O2 treatment increased LP and PC levels and decreased CAT activity. GSH levels were similar in control and treated MFs. CONCLUSION: H2 O2 caused oxidative damage in both LMF and HMF and the antioxidant system measured in these two MFs responded similarly. To the best of our knowledge, this is the first partial description of the antioxidant defense in placental HMF and LMF performed in a cell-free assay. The small number of antioxidant system parameters measured did not allow detecting differences between HMF and LMF.

Maternal hypertension and feto-placental growth restriction is reversed by sildenafil: Evidence of independent effects of circulating nitric oxide levels.

Sildenafil has shown nitric oxide (NO)-independent pleiotropic effects, however the mechanisms involved are unclear. We investigated the protective effects of sildenafil against hypertension in pregnancy and feto-placental growth restriction induced by NO inhibition, and if sodium nitrite-derived NO formation influences sildenafil effects. We evaluated the plasmatic levels of NO metabolites, cyclic guanosine monophosphate (cGMP), oxidative stress and myeloperoxidase, which are involved in endothelial dysfunction during hypertension in pregnancy. Also, we performed in vitro experiments to examine cell viability and NO synthesis in human umbilical vein endothelial cells (HUVECs) cultures incubated with plasma from healthy or hypertensive pregnant rats treated (or not) with both drugs, either alone or in association. Sildenafil blunted hypertension in pregnancy and protected against feto-placental growth restriction induced by NO inhibition and these effects of sildenafil alone were similar to those presented by its association with sodium nitrite. Protective effects of sildenafil were observed even with low plasmatic NO levels and were not followed by increases in cGMP levels. Also, sildenafil, but not sodium nitrite, blunted the increases in myeloperoxidase activity. Both drugs (isolated or in association) presented antioxidant effects. Plasma from hypertensive pregnant rats treated with sildenafil, but not sodium nitrite alone, increased the viability of HUVECs. NO synthesis in HUVECs cultures was increased with plasma from rats treated with both drugs. We conclude that sildenafil effects are not dependent of circulating NO levels in hypertension and feto-placental growth restriction. These findings may reflect a protection against myeloperoxidase and pro-oxidant activation in hypertension in pregnancy.

Involvement of leptin in the molecular physiology of the placenta.

Leptin is a homeostatic regulator in the placenta where it promotes proliferation, protein synthesis and the expression of tolerogenic maternal response molecules such as HLA-G. Leptin also exerts an anti-apoptotic action in placenta controlling the expression of p53 master cell cycle regulator under different stress conditions. On the other hand, leptin is an integrative target of different placental stimuli. The expression of leptin in placenta is regulated by hCG, insulin, steroids, hypoxia and many other growth hormones, suggesting that it might have an important endocrine function in the trophoblastic cells. The leptin expression is induced involving the cAMP/PKA or cAMP/Epac pathways which have profound actions upon human trophoblast function. The activation of PI3K and MAPK pathways also participates in the leptin expression. Estrogens play a central role during pregnancy, particularly 17ß-estradiol upregulates the leptin expression in placental cells through genomic and non-genomic actions. The leptin promoter analysis reveals specific elements that are active in placental cells. The transcription factors CREB, AP1, Sp1, NFκB and the coactivator CBP are involved in the placental leptin expression. Moreover, placental leptin promoter is a target of epigenetic marks such as DNA methylation and histone acetylation that regulates not only the leptin expression in placenta during pregnancy but also determines the predisposition of acquiring adult metabolism diseases. Taken together, all these results allow a better understanding of leptin function and regulatory mechanisms of leptin expression in human placental trophoblasts, and support the importance of leptin during pregnancy and in programming adult health.

Placental contribution to the endocrinology of gestation and parturition

In addition to many other functions, the placenta is a source of a vast number of autocrine, paracrine and endocrine factors. However, the spectrum of placental regulatory factors, their concentrations, gestational profiles and roles may differ considerably even between phylogenetically closely related species. Depending on the species, placental regulatory factors of a broad range of molecule classes have been found including (glyco- )proteins, peptides, steroids and prostaglandins. Local placental regulatory factors are especially important for the dialogue between the fetal and the maternal compartment immediately at the feto-maternal borderline and for the control of growth, differentiation and functions of the placenta itself. Moreover, placental hormones in a proper sense may also have effects in more remote targets within the maternal compartment, serving functions such as pregnancy-specific adaptations of maternal circulation, provision of hemotrophe to the fetus or the development and function of the mammary gland. Functions of placental hormones in the fetus proper are less clear but may be especially important before the establishment of a functional fetal endocrine system and near term within the highly species-specific networks of signals preparing and initiating parturition. This review takes a comparative view on the situation in different domestic animals focusing on ruminants and on placental hormones occurring at significant concentrations in the maternal circulation.(AU)

Impact of thermal stress on placental function and fetal physiology

In ruminants, prolonged exposure to high ambient temperatures negatively affects placental development and function. The pursuing limitations in placental oxygen and nutrient supply between the mother and fetus slow fetal growth lowering birth weights and postnatal performance. The pregnant ewe is a long-standing animal model for the study of maternalfetal interactions and is susceptible to naturally occurring heat stress, which causes fetal growth restriction. In the pregnant ewe, studies show that the fetus adapts to hyperthermia-induced placental insufficiency to preserve placental transport capacity of oxygen and nutrients. These adaptive responses are at the expense of normal fetal development and growth. Enlarged transplacental gradient for oxygen and glucose facilitates diffusion across the placenta, but develops by lowering fetal blood oxygen and glucose concentrations. Fetal hypoxemia and hypoglycemia slow growth and alter their metabolic and endocrine profiles. Deficits in amino acids transport across the placenta are present but are overcome by reduced fetal clearance rates, likely due to fetal hypoxemia or endocrine responses to hypoxic stress. Here, we provide an overview of the performance limitations observed in ruminants exposed to heat stress during pregnancy, but we focus our presentation on the sheep fetus in pregnancies complicated by hyperthermia-induced placental insufficiency. We define the characteristics of placental dysfunction observed in the fetus of heat stressed ewes during pregnancy and present developmental adaptations in organogenesis, metabolism, and endocrinology that are proposed to establish maladaptive situations reaching far beyond the perinatal period.(AU)

Placental contribution to the endocrinology of gestation and parturition

In addition to many other functions, the placenta is a source of a vast number of autocrine, paracrine and endocrine factors. However, the spectrum of placental regulatory factors, their concentrations, gestational profiles and roles may differ considerably even between phylogenetically closely related species. Depending on the species, placental regulatory factors of a broad range of molecule classes have been found including (glyco- )proteins, peptides, steroids and prostaglandins. Local placental regulatory factors are especially important for the dialogue between the fetal and the maternal compartment immediately at the feto-maternal borderline and for the control of growth, differentiation and functions of the placenta itself. Moreover, placental hormones in a proper sense may also have effects in more remote targets within the maternal compartment, serving functions such as pregnancy-specific adaptations of maternal circulation, provision of hemotrophe to the fetus or the development and function of the mammary gland. Functions of placental hormones in the fetus proper are less clear but may be especially important before the establishment of a functional fetal endocrine system and near term within the highly species-specific networks of signals preparing and initiating parturition. This review takes a comparative view on the situation in different domestic animals focusing on ruminants and on placental hormones occurring at significant concentrations in the maternal circulation.

Impact of thermal stress on placental function and fetal physiology

In ruminants, prolonged exposure to high ambient temperatures negatively affects placental development and function. The pursuing limitations in placental oxygen and nutrient supply between the mother and fetus slow fetal growth lowering birth weights and postnatal performance. The pregnant ewe is a long-standing animal model for the study of maternalfetal interactions and is susceptible to naturally occurring heat stress, which causes fetal growth restriction. In the pregnant ewe, studies show that the fetus adapts to hyperthermia-induced placental insufficiency to preserve placental transport capacity of oxygen and nutrients. These adaptive responses are at the expense of normal fetal development and growth. Enlarged transplacental gradient for oxygen and glucose facilitates diffusion across the placenta, but develops by lowering fetal blood oxygen and glucose concentrations. Fetal hypoxemia and hypoglycemia slow growth and alter their metabolic and endocrine profiles. Deficits in amino acids transport across the placenta are present but are overcome by reduced fetal clearance rates, likely due to fetal hypoxemia or endocrine responses to hypoxic stress. Here, we provide an overview of the performance limitations observed in ruminants exposed to heat stress during pregnancy, but we focus our presentation on the sheep fetus in pregnancies complicated by hyperthermia-induced placental insufficiency. We define the characteristics of placental dysfunction observed in the fetus of heat stressed ewes during pregnancy and present developmental adaptations in organogenesis, metabolism, and endocrinology that are proposed to establish maladaptive situations reaching far beyond the perinatal period.

Ultrastructure of bovine placenta during all gestational period / Ultraestrutura de placenta bovina durante todo o período gestacional

Placentas from pregnant cows with different gestation periods were used. Placental fragments of all groups were processed and evaluated by transmission electron microscopy. After fragment analysis, bovine placenta was observed to be epitheliochorial type in early pregnancy, becoming progressively sinepiteliocorial at the beginning of the second trimester. There are no ultrastructural evidences of inflammation in the region of caruncles throughout gestation, despite the invasion of caruncle proper lamina by trophoblast cells. However, throughout pregnancy and especially at the end, there were evident signs of cell degeneration in both trophoblast and the uterine epithelium. The active trophoblast cells intensely phagocytize cellular debris. There are complex interdigitations between the surface of the trophoblast and the uterine epithelium, which is related to the increase of the exchange surface between mother and fetus. At the end of pregnancy, interdigitations disappear, favoring the detachment and expulsion of the placenta after birth.(AU)

Foram utilizadas placentas de vacas abatidas em frigorífico com diversos tempos gestacionais. Fragmentos de placentomo de todos os grupos foram processados e avaliados em microscopia eletrônica de transmissão. Após análise dos fragmentos, observou-se que a placenta bovina é do tipo epiteliocorial no início da gestação, tornando-se sinepiteliocorial progressivamente a partir do início do segundo mês de gestação. Não existem evidências ultraestruturais de inflamação na região das carúnculas durante toda a gestação, apesar da invasão da lâmina própria caruncular por células trofoblásticas. No entanto, durante toda a gestação e em especial ao seu final, foram observados sinais evidentes de degeneração celular, tanto do trofoblasto como do epitélio uterino. As células trofoblásticas ativas fagocitam intensamente os debris celulares originados dessas degenerações. Existem complexas interdigitações entre a superfície do trofoblasto e do epitélio uterino, o que estaria relacionado com o aumento da superfície de troca entre mãe e feto. Ao final da gestação, praticamente desaparecem essas interdigitações, favorecendo o descolamento e a expulsão da placenta após o parto.(AU)

Ultrastructure of bovine placenta during all gestational period / Ultraestrutura de placenta bovina durante todo o período gestacional

Placentas from pregnant cows with different gestation periods were used. Placental fragments of all groups were processed and evaluated by transmission electron microscopy. After fragment analysis, bovine placenta was observed to be epitheliochorial type in early pregnancy, becoming progressively sinepiteliocorial at the beginning of the second trimester. There are no ultrastructural evidences of inflammation in the region of caruncles throughout gestation, despite the invasion of caruncle proper lamina by trophoblast cells. However, throughout pregnancy and especially at the end, there were evident signs of cell degeneration in both trophoblast and the uterine epithelium. The active trophoblast cells intensely phagocytize cellular debris. There are complex interdigitations between the surface of the trophoblast and the uterine epithelium, which is related to the increase of the exchange surface between mother and fetus. At the end of pregnancy, interdigitations disappear, favoring the detachment and expulsion of the placenta after birth.(AU)

Foram utilizadas placentas de vacas abatidas em frigorífico com diversos tempos gestacionais. Fragmentos de placentomo de todos os grupos foram processados e avaliados em microscopia eletrônica de transmissão. Após análise dos fragmentos, observou-se que a placenta bovina é do tipo epiteliocorial no início da gestação, tornando-se sinepiteliocorial progressivamente a partir do início do segundo mês de gestação. Não existem evidências ultraestruturais de inflamação na região das carúnculas durante toda a gestação, apesar da invasão da lâmina própria caruncular por células trofoblásticas. No entanto, durante toda a gestação e em especial ao seu final, foram observados sinais evidentes de degeneração celular, tanto do trofoblasto como do epitélio uterino. As células trofoblásticas ativas fagocitam intensamente os debris celulares originados dessas degenerações. Existem complexas interdigitações entre a superfície do trofoblasto e do epitélio uterino, o que estaria relacionado com o aumento da superfície de troca entre mãe e feto. Ao final da gestação, praticamente desaparecem essas interdigitações, favorecendo o descolamento e a expulsão da placenta após o parto.(AU)