RESUMO
In amniotic vertebrates (birds, reptiles and mammals), an extraembryonic structure called the chorioallantoic membrane (CAM) functions as respiratory organ for embryonic development. The CAM is derived from fusion between two pre-existing membranes, the allantois, a hindgut diverticulum and a reservoir for metabolic waste, and the chorion which marks the embryo's external boundary. Modified CAM in eutherian mammals, including humans, gives rise to chorioallantoic placenta. Despite its importance, little is known about cellular and molecular mechanisms mediating CAM formation and maturation. In this work, using the avian model, we focused on the early phase of CAM morphogenesis when the allantois and chorion meet and initiate fusion. We report here that chicken chorioallantoic fusion takes place when the allantois reaches the size of 2.5-3.0 mm in diameter and in about 6 hours between E3.75 and E4. Electron microscopy and immunofluorescence analyses suggested that before fusion, in both the allantois and chorion, an epithelial-shaped mesothelial layer is present, which dissolves after fusion, presumably by undergoing epithelial-mesenchymal transition. The fusion process per se, however, is independent of allantoic growth, circulation, or its connection to the developing mesonephros. Mesoderm cells derived from the allantois and chorion can intermingle post-fusion, and chorionic ectoderm cells exhibit a specialized sub-apical intercellular interface, possibly to facilitate infiltration of allantois-derived vascular progenitors into the chorionic ectoderm territory for optimal oxygen transport. Finally, we investigated chorioallantoic fusion-like process in primates, with limited numbers of archived human and fresh macaque samples. We summarize the similarities and differences of CAM formation among different amniote groups and propose that mesothelial epithelial-mesenchymal transition mediates chorioallantoic fusion in most amniotic vertebrates. Further study is needed to clarify tissue morphogenesis leading to chorioallantoic fusion in primates. Elucidating molecular mechanisms regulating mesothelial integrity and epithelial-mesenchymal transition will also help understand mesothelial diseases in the adult, including mesothelioma, ovarian cancer and fibrosis. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
Assuntos
Alantoide , Membrana Corioalantoide , Alantoide/metabolismo , Animais , Córion/metabolismo , Epitélio , Humanos , Mamíferos , Oxigênio/metabolismoRESUMO
During the early development of Placentalia, a distinctive projection emerges at the posterior embryonic-extraembryonic interface of the conceptus; its fingerlike shape presages maturation into the placental umbilical cord, whose major role is to shuttle fetal blood to and from the chorion for exchange with the mother during pregnancy. Until recently, the biology of the cord's vital vascular anlage, called the body stalk/allantois in humans and simply the allantois in rodents, has been largely unknown. Here, new insights into the development of the mouse allantois are featured, from its origin and mechanism of arterial patterning through its union with the chorion. Key to generating the allantois and its critical functions are the primitive streak and visceral endoderm, which together are sufficient to create the entire fetal-placental connection. Their newly discovered roles at the embryonic-extraembryonic interface challenge conventional wisdom, including the physical limits of the primitive streak, its function as sole purveyor of mesoderm in the mouse, potency of visceral endoderm, and the putative role of the allantois in the germ line. With this working model of allantois development, understanding a plethora of hitherto poorly understood orphan diseases in humans is now within reach. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
Assuntos
Alantoide , Placenta , Alantoide/irrigação sanguínea , Animais , Embrião de Mamíferos , Feminino , Humanos , Mesoderma , Camundongos , Gravidez , Linha PrimitivaRESUMO
Although fetal fluids, amnion (AM) and allantois (AL), have been studied at the end of pregnancy in the bitch, little is known about their composition during gestation. The aim of this study was to characterize and compare the biochemical parameters of fetal fluids collected from healthy pregnant bitches in mid pregnancy. Fetal fluids were collected from 26 pregnant bitches between 35 and 62 days from ovulation based on ultrasonography. A total of 149 samples were analyzed; 94 samples of known origin (61 a.m. and 33 AL) from 17 dams, which included 17 paired samples (AM and AL from the same fetus; 34 samples), and 55 of unknown origin from nine dams. Reference ranges were formulated for 22 biochemical parameters in AM and AL based on the samples of known origin (n = 94). All parameters (creatinine, albumin, GGT and urea) significantly different between AM and AL were included (by mixed model ANOVA) in the analysis and an algorithm to predict the origin of the fluid was developed (by logistic regression). Overall, of the 94 samples, 79 samples (84%) were correctly identified by the algorithm. For the 33 allantois samples, and for the 61 amnion samples, 23 (69.7%) and 56 (91.8%) were correctly identified by the algorithm, respectively. Based on the algorithm, 31 of the unknown samples (58%) were classified as amnion and 22 samples (42%), as allantois fluid. For all the unknown samples, the average certainty was 86% (compared to 81% for the samples whose fluid type was known), showing the degree of precision of the classification.
Assuntos
Líquido Amniótico , Líquidos Corporais , Alantoide , Líquido Amniótico/química , Animais , Líquidos Corporais/química , Cães , Feminino , Gravidez , UreiaRESUMO
Intrauterine mobility of the fetal-amniotic unit is unique in equids among domestic species. Intrinsic activity begins as head nods on â¼ Day 40 (Day 0 = ovulation) and by Day 60 has progressed into intermittent subtle to vigorous head, neck, limb, and body movements. On Days 60-100, fetal mobility is maximal with traveling of the fetal-amniotic unit throughout an allantoic pool that encompasses the uterine horns, and uterine body. The fetus may be entirely within one uterine horn with the horn entrance closed behind it, and then may work through the entrance into the uterine body. Mobility gradually decreases after Day 100 with a decrease in relative quantity of allantoic fluid but intrinsic activity continues. Changes in each of fetal intrauterine location, presentation, and recumbency can occur frequently (e.g., 5-minutes intervals). About 80% of fetal mobility is from the propulsive effects of intrinsic fetal activities, and the remainder is from currents and shifts in the allantoic pool. The fluid currents are attributable to transient uterine constrictions that vary from 10 mm in width to the length of a uterine horn and to extrinsic mare and adjacent visceral activity. The fetus is tethered by a long umbilical cord attached at the mid-uterus allowing travel throughout an allantoic sac that involves the entire uterus. The mobile fetus seemingly practices the neuromuscular coordination that it will need during independent life. The theriogenologist can educate and fascinate onlookers by ultrasound demonstrations of bursts of fetal activity and mobility. An online video is included.
Assuntos
Feto , Útero , Alantoide , Animais , Feminino , Movimento Fetal , Cavalos , OvulaçãoRESUMO
BACKGROUND: Fluorescence-guided surgery (FGS) with 5-aminolevulinic acid (5-ALA) and other contrast agents has shown its efficacy in improving resection margins, local recurrence and survival rates in several medical disciplines. It is the objective of this study to analyze the engraftment rate of musculoskeletal tumor specimens on the chick chorio-allantoic membrane (CAM), the rate of tumor fluorescence (PDD), and the effects of photodynamic therapy (PDT) after exposure of tumors to 5-ALA in an in vivo environment. METHODS: A total of 486 CAMs were inoculated with macroscopic tumor grafts (n = 26; n = 478 eggs) and primary cell culture suspensions (n = 2; n = 8 eggs) from 26 patients on day 10 of egg development. On day 16, 2 mg/200 µl 5-ALA were topically applied per egg. After 4 h of incubation, Protoporphyrin IX was excited using blue light (420 ± 10 nm). Tumor fluorescence (PDD) was photo-documented. A subgroup of specimens was additionally exposed to red light (635 nm ± 10 nm; PDT). After the termination of the experiment, CAM-grown tumors were histopathologically analyzed. RESULTS: Benign and borderline tumors (chondroblastoma, giant cell tumor of bone and atypical chondrogenic tumor) presented with high rates of detectable fluorescence. Comparable results were found for chondrosarcoma, osteosarcoma and Ewing's sarcoma among bone and dedifferentiated liposarcoma, myxofibrosarcoma and undifferentiated pleomorphic sarcoma among soft tissue sarcomas. Overall, tumor fluorescence was negative for 20.2%, single-positive (+) for 46.9% and double-positive (++) for 32.9% of macroscopic xenografts, and negative in 20% and (+) in 80% of primary cell culture tumors. Macroscopic tumor xenografts (n = 478) were identified as viable in 14.8%, partially viable in 2.9% and partially to completely regressive in 45.2%. All (n = 8) tumors grown from primary cell culture were viable. After PDT, tumor samples were found viable in 5.5%, partially viable in 5.5% and partially to completely regressive in 68%. Egg survival increased with decreasing PDT doses. CONCLUSIONS: The CAM model proves to be a suitable in vivo model for the investigation of short-term observation questions in musculoskeletal tumors. The findings of this study warrant further investigation of PDT effects on musculoskeletal tumors and a possible incorporation of 5-ALA FGS in clinical Orthopedic Oncology care.
Assuntos
Ácido Aminolevulínico , Fluorescência , Procedimentos Ortopédicos , Cirurgia Assistida por Computador/métodos , Oncologia Cirúrgica , Alantoide , Ácido Aminolevulínico/farmacologia , Animais , Embrião de Galinha , Meios de Contraste , Corantes Fluorescentes , Fotoquimioterapia , Sensibilidade e EspecificidadeRESUMO
Relatively little is known about allantois and urachal development in early humans.Serial sagittal histological sections from eight human embryos and fetuses were examined to determine allantois development.At gestational age 6-7 weeks, the primitive allantois consists of an enlarged tube located between the umbilical cord and abdominal cavity, whereas the urachus is not yet developed. At 8 weeks, the allantois gradually withdraws from the distal to the proximal end of the umbilical cord, and both the proximal allantois and the rectum (hindgut) start to develop into the cloaca. At 10 weeks, the allantois was located mostly in the abdominal cavity.The urachus forms from the distal end of the allantois and develops into a closed fibrous cord between the base of the urinary bladder and the umbilicus. The urogenital sinus forms from the proximal end of the allantois.
Assuntos
Úraco , Humanos , Lactente , Úraco/patologia , Alantoide , Umbigo , Bexiga Urinária , Cordão UmbilicalRESUMO
After the cessation of equine embryo mobility (fixation) on mean Day 16, the embryonic vesicle is rotated or oriented so that the pole with the embryo proper is opposite to the mesometrial attachment. Orientation involves massage of the vesicle by contractions of the turgid uterine horn and greater thickening of the vesicle at the pole with the embryo proper. Thickening of the dorsal endometrium (encroachment) especially on each side of the mesometrial attachment accounts for a guitar-pick shape of the vesicle when viewed in cross section of the uterine horn. On Days 21-40, the allantoic sac expands, and the relative size of the yolk sac diminishes highlighted by carrying of the embryo proper to the dorsal aspect of the embryonic vesicle. There, the blood vessels from the embryonic vesicle meet at the mesometrial attachment to become the beginning of the umbilical cord. At the end of the embryo stage and beginning of the fetal stage (Day 40), the umbilical cord lengthens in association with the descent of the fetus to the bottom of the allantoic sac. After unilateral fixation of twins, a natural embryo reduction process frequently (â¼85%) eliminates one of the embryos. The twins are massaged by the uterine contractions, and a critical proportion of the thicker wall of the doomed embryonic vesicle is forced into the thinner wall of the survivor. Natural embryo reduction does not occur for bilateral twins and reduction requires intervention from the theriogenologist.
Assuntos
Embrião de Mamíferos , Endométrio , Alantoide , Animais , Feminino , Cavalos , Gravidez , Contração Uterina , ÚteroRESUMO
When human influenza viruses are isolated and passaged in chicken embryos, variants with amino acid substitutions around the receptor binding site of hemagglutinin (HA) are selected; however, the mechanisms that underlie this phenomenon have yet to be elucidated. Here, we analyzed the receptor structures that contributed to propagation of egg-passaged human H1N1 viruses. The analysis included seasonal and 2009 pandemic strains, both of which have amino acid substitutions of HA found in strains isolated or passaged in eggs. These viruses exhibited high binding to sulfated glycans containing NeuAcα2-3Gal. In MDCK cells overexpressing the sulfotransferase that synthesize Galß1-4(SO3--6)GlcNAc, production of human H1N1 viruses was increased up to 90-fold. Furthermore, these sulfated glycans were expressed on the allantoic and amniotic membranes of chicken embryos. These results suggest that 6-sulfo sialyl Lewis X and/or NeuAcα2-3Galß1-4(SO3--6)GlcNAc are involved in efficient propagation of human H1N1 viruses in chicken embryos.
Assuntos
Embrião de Galinha/virologia , Vírus da Influenza A Subtipo H1N1/crescimento & desenvolvimento , Polissacarídeos/metabolismo , Sulfatos/metabolismo , Alantoide/metabolismo , Âmnio/metabolismo , Animais , Embrião de Galinha/metabolismo , Cães , Galactosídeos/química , Galactosídeos/metabolismo , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/metabolismo , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/metabolismo , Células Madin Darby de Rim Canino , Mutação , Ácido N-Acetilneuramínico/química , Ácido N-Acetilneuramínico/metabolismo , Polissacarídeos/química , Receptores Virais/metabolismo , Sulfatos/química , Sulfotransferases/genética , Sulfotransferases/metabolismoRESUMO
This study evaluated the uterine and fetal morphometric changes and fetal membrane fluids biochemistry across the gestation of Yankasa sheep. The amniotic and allantoic fluids are actively involved in the constant physiologic exchange between the fetus and maternal circulation. Hence, the knowledge regarding changes in the composition of fetal membrane fluids is important for understanding fetal metabolism, and the diagnosis of pathophysiological conditions during gestation. Gravid uteri from 37 ewes and their corresponding ovaries were sampled. The number and size of the placentomes in the second and third terms of gestation were significantly higher relative to the first term. The total protein, albumin, glucose, urea, creatinine, and calcium levels as well as alkaline phosphatase (ALP) and aspartate aminotransferase (AST) activities were higher in the allantoic fluid. In the allantoic fluid, the levels of total protein, globulin, and the activity levels of ALT and AST increased progressively with the advancement of gestation; contrarily, the levels of calcium, chloride, and the activity level of ALT decreased. For the amniotic fluid, the levels of total protein, globulin, urea, calcium, and the enzyme activities in the second and third terms did not differ but were higher than the level in the first term of gestation. In addition, the most significant increases in creatinine level and white blood cell count were observed in the third term of gestation. Therefore, notable differences in the levels of ALT, AST, total proteins, glucose, urea, creatinine, and WBC counts were observed in the two fetal membrane fluids.
Assuntos
Líquido Amniótico , Ovário , Alantoide , Âmnio , Animais , Feminino , Feto , Gravidez , Ovinos , ÚteroRESUMO
Solid tumors and metastasis rely on angiogenesis for sufficient supply as they grow, making antiangiogenic treatment a promising option in the combat of cancer. Testing of inhalants on the chorio-allantoic membrane offers a simple but precise method to assess the impact on angiogenesis. The in ovo testing method can be used to directly determine the effect of inhaled formulations solely or in the context of photodynamic therapy. In this study curcumin liposomes served as a model for testing of pulmonary application and revealed an excellent antiangiogenetic effect. This efficacy of a model inhalant illustrates the suitability of the method.
Assuntos
Alantoide , MorfogêneseRESUMO
Inoculation of embryonated chicken eggs has been widely used during the past decades; however, inoculation success rates have not been investigated systematically. In this study named success rates were assessed in brown eggs incubated between 5 and 19 days, which were inoculated with 0.2â ml methylene blue per egg. Inoculations were performed in a simple and fully standardized way. Five embryonic compartments were targeted blindly (amniotic cavity, embryo, allantoic cavity, albumen and yolk) with needles of four different lengths; albumen and yolk were targeted with eggs in upside down position. Three compartments were inoculated within sight (air chamber, chorioallantoic membrane and blood vessel). Twenty embryos were used per incubation day, intended deposition site and needle length. Success rates were assessed by visual inspection after breaking the eggs. The inoculations targeting albumen, yolk, amniotic cavity and embryo yielded low scores. Magnetic resonance imaging was performed to elucidate the reason(s) for these low success rates: needles used were of appropriate length, but embryo and amniotic cavity had variable positions in the eggs, while albumen and yolk rapidly changed position after turning the eggs upside down. The latter led to adjustment of the inoculation method for albumen and yolk. Failures to inoculate compartments within sight were immediately visible; therefore, these eggs could be discarded. Except for the amniotic cavity, full scores (20/20) were obtained for all compartments although not always on every day of incubation. In conclusion, the present study may serve as a guide to more accurately inoculate the various chicken embryo compartments. RESEARCH HIGHLIGHTS Blind inoculation of embryonated egg compartments was successful, except for the amniotic cavity. MRI showed rapid position change of albumen and yolk after turning eggs upside down. In ovo vaccination against Marek's disease might be improved by using 38â mm needles.
Assuntos
Doença de Marek/virologia , Óvulo/ultraestrutura , Alantoide/ultraestrutura , Alantoide/virologia , Âmnio/ultraestrutura , Âmnio/virologia , Animais , Embrião de Galinha , Membrana Corioalantoide/ultraestrutura , Membrana Corioalantoide/virologia , Feminino , Injeções , Imageamento por Ressonância Magnética/veterinária , Masculino , Azul de Metileno , Óvulo/virologiaRESUMO
Physiological parturition is characterized by sterile, inflammatory-like processes. During parturition, the placenta expresses various proinflammatory mediators, such as chemokines and IL-17. Nevertheless, inflammatory processes present in the parturient mare are poorly characterized. The aim of this study was to investigate the expression of selected chemokines and IL-17 in the allantochorion and the endometrium of mares that retained fetal membranes (RFM) and expelled them physiologically. We hypothesized that the expression of these mediators may be altered in the placenta of mares with RFM and result in RFM occurrence. Differences in mRNA expression in the placenta of investigated groups of mares were detected for CCL2, CCL3, CCL4, CCL8, CXCL1, CXCL8, CXCL10, CX3CL1 and IL-17. There were no differences in mRNA expression of CCL5 and CXCL6. Gene ontology network analysis showed enrichment in genes related to leukocyte migration, cell chemotaxis and response to chemokine in tissues of RFM mares. Analysis of association network suggested denotations between CXCL6, CXCL8, CXCL1, CCL5, CCL4, CX3CL1 and CXCL10. Moreover, possible inhibition of CXCL10 by IL-17A and prostaglandin peroxide synthase 2 (PTGS2) by CXCL1 was detected. Our results suggest that, based on differences in chemokines and IL-17 expression, recruited subsets of leukocytes might differ between the analyzed groups of mares, which in turn may impair the separation of fetal membranes in the group of RFM mares. In addition, the results of the expression analysis suggest that macrophages might be one of the most abundant cells infiltrating the equine placenta during the expulsion of fetal membranes. Furthermore, we suspect that the synthesis of PTGS2 might be inhibited in mares with RFM.
Assuntos
Quimiocinas/genética , Membranas Extraembrionárias/metabolismo , Perfilação da Expressão Gênica/métodos , Mediadores da Inflamação/metabolismo , Interleucina-17/genética , Placenta/metabolismo , Alantoide/metabolismo , Animais , Quimiocinas/metabolismo , Córion/metabolismo , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Endométrio/metabolismo , Feminino , Cavalos , Interleucina-17/metabolismo , GravidezRESUMO
The amniotic and allantoic fluid compartments in the mare serve essential roles throughout pregnancy and parturition. Although the global metabolomic profile of amniotic fluid in women has been extensively characterized, current data for equine fetal fluids are limited. Therefore, the goal of this study was to characterize the global metabolomic profile of equine allantoic and amniotic fluid through nuclear magnetic resonance spectroscopy. Fetal fluids were collected between 270 and 295 days of gestation from 12 pregnancies through ultrasound-guided transabdominal puncture. A total of 24 samples (n = 10 allantoic fluid; n = 9 amniotic fluid; n = 5 admixed fluid) were analyzed by one-dimensional proton (1H) and two-dimensional (1H-13 C) nuclear magnetic resonance spectroscopy. Metabolites were integrated and compared between fluid types using a Kruskal-Wallis test at P < .05 significance. A total of 28 distinct metabolites were found in allantoic and admixed fluid, whereas 23 metabolites were identified in amniotic fluid. Allantoic fluid contained significant elevations (P < .05) in the metabolites betaine, creatine, creatinine, citrate, histidine, nitrophenol, tryptophan, π-methylhistidine, and unknown metabolite #1 compared with amniotic fluid, whereas amniotic fluid contained statistically increased concentrations of the metabolite lactate compared with allantoic fluid (P = .003).
Assuntos
Líquido Amniótico , Líquidos Corporais , Alantoide , Animais , Feminino , Cavalos , Espectroscopia de Ressonância Magnética , Gravidez , PrótonsRESUMO
The extra-embryonic hypoblast/visceral endoderm of Placentalia carries out a variety of functions during gestation, including hematopoietic induction. Results of decades-old and recent experiments have provided compelling evidence that, in addition to its inducing properties, hypoblast/visceral endoderm itself is a source of placental blood cells. Those observations that highlight extra-embryonic endoderm's role as an overlooked source of placental blood cells across species are briefly discussed here, with suggestions for future exploration.
Assuntos
Alantoide/citologia , Células Sanguíneas/citologia , Endoderma/citologia , Eritroblastos/citologia , Placenta/citologia , Saco Vitelino/citologia , Alantoide/crescimento & desenvolvimento , Alantoide/metabolismo , Animais , Células Sanguíneas/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Endoderma/crescimento & desenvolvimento , Endoderma/metabolismo , Eritroblastos/metabolismo , Feminino , Proteínas Fetais/genética , Proteínas Fetais/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Camundongos , Fator 3 de Transcrição de Octâmero/genética , Fator 3 de Transcrição de Octâmero/metabolismo , Receptor Patched-1/genética , Receptor Patched-1/metabolismo , Placenta/metabolismo , Gravidez , Proteínas com Domínio T/genética , Proteínas com Domínio T/metabolismo , Saco Vitelino/crescimento & desenvolvimento , Saco Vitelino/metabolismoRESUMO
The embryonated egg is a complex structure comprised of an embryo and its supporting membranes (chorioallantoic, amniotic, and yolk). The developing embryo and its membranes provide a diversity of cell types that allow for the successful replication of a wide variety of different viruses. Within the family Coronaviridae the embryonated egg has been used as a host system primarily for two avian coronaviruses within the genus Gammacoronavirus, infectious bronchitis virus (IBV) and turkey coronavirus (TCoV). IBV replicates well in the embryonated chicken egg, regardless of inoculation route; however, the allantoic route is favored as the virus replicates well in epithelium lining the chorioallantoic membrane, with high virus titers found in these membranes and associated allantoic fluids. TCoV replicates only in epithelium lining the embryo intestines and bursa of Fabricius; thus, amniotic inoculation is required for isolation and propagation of this virus. Embryonated eggs also provide a potential host system for detection, propagation, and characterization of other, novel coronaviruses.
Assuntos
Embrião de Galinha/virologia , Coronavirus do Peru/isolamento & purificação , Vírus da Bronquite Infecciosa/isolamento & purificação , Alantoide/virologia , Âmnio/virologia , Animais , Embrião de Galinha/citologia , Coronavirus do Peru/fisiologia , Vírus da Bronquite Infecciosa/fisiologia , Tropismo ViralRESUMO
The equine placenta is a simple apposition of fetal and maternal tissues, becoming more complex with the formation of microcotyledons around days 75 and 100 of gestation. The present study aimed to describe the gross and microscopic morphology of early equine placenta. Embryonic/fetal membranes from thirty-seven mares were submitted to macroscopic description, light, scanning and transmission microscopy. Overall the gross characteristics of membranes were similar with already described for older stages. However, transmission electron microscopy evidenced high metabolic rate in chorion and allantois, and high secretion profile in amnion and even higher in yolk sac. Gene ontologies enrichment, using published data, pointed several common ontologies in allantoic and amniotic fluids, related to oxygen and iron transport, extracellular space and high-density lipoprotein receptor binding. Overall, the morphological and ontology enrichment could indicate allantois and amnion crosstalk.
La placenta equina es una simple aposición de tejidos fetales y maternos, que se vuelve más compleja con la formación de microcotiledones alrededor de los días 75 y 100 de gestación. El presente estudio tuvo como objetivo describir la morfología macroscópica y microscópica de la placenta equina temprana. Las membranas embrionarias / fetales de treinta y siete yeguas fueron sometidas a descripción macroscópica, luz, escaneo y microscopía de transmisión. En general, las características generales de las membranas fueron similares a las ya descritas para las etapas más antiguas. Sin embargo, la microscopía electrónica de transmisión mostró una alta tasa metabólica en corion y alantoides, y un alto perfil de secreción en amnios e incluso mayor en el saco vitelino. El enriquecimiento de ontologías génicas, utilizando datos publicados, señaló varias ontologías comunes en fluidos alantoideos y amnióticos, relacionados con el transporte de oxígeno y hierro, espacio extracelular y unión a receptores de lipoproteínas de alta densidad. En general, el enriquecimiento morfológico y ontológico podría indicar alantoides y diafonía de amnios.
Assuntos
Animais , Feminino , Gravidez , Placenta/anatomia & histologia , Cavalos , Placenta/ultraestrutura , Primeiro Trimestre da Gravidez , Córion , Alantoide , Âmnio , Microscopia/métodosRESUMO
A total of 127 normal placentas from Arabian mares resident in the United Arab Emirates were examined. The mean linear dimensions of the placenta were, on average, 84% of those previously recorded for the placentas of the Thoroughbred. Significant differences in the size of the allantochorion between primigravid and multiparous mares were seen only in the linear dimensions of the body portion. The pregnant horn was more commonly on the right than left side of the uterus (P = .01; 74/127; 58%). Cord attachment was primarily at the base of the two placental horns (112/127; 88%), with the remainder showing anomalies from this position. The mean (±SEM) total length of the umbilical cords was 62.2 ± 1.2 cm, being composed of the allantoic portion (29.7 ± 0.9 cm) and amniotic portion (32.5 ± 0.6 cm), which averaged 53 ± 0.01% of the total length. The amniotic portion was usually, but not always, longer than the allantoic portion (79/127; 62%). Longer cords were associated with a greater proportion of allantoic length. An enlarged yolk sac remnant (YSR) was present in 16/127 (13%) placentas. Cords with YSRs displayed a significantly longer allantoic portion than those without (P = .02). The total cord length was not correlated with the weight or area of the allantochorion or amnion, any linear measurement of the allantochorion, gestation length, the month of foaling, parity of the dam, or birthweight or sex of the foal. The purpose for which the mare was bred (i.e., racing or showing) influenced the cord length, those of show mares being significantly longer.
Assuntos
Placenta , Cordão Umbilical , Alantoide , Animais , Peso ao Nascer , Feminino , Cavalos , Gravidez , Emirados Árabes UnidosRESUMO
INTRODUCTION: Hydrallantois is the excessive accumulation of fluid in the allantoic cavities during the last trimester of pregnancy, leading to abdominal wall hernias, cardiovascular shock, abortion, and dystocia. It has been postulated that hydrallantois is associated with structural and/or functional changes in the chorioallantoic membrane. In the present study, we hypothesized that angiogenesis is impaired in the hydrallantoic placenta. METHOD: Capillary density in the hydrallantoic placenta was evaluated in the chorioallantois via immunohistochemistry for Von Willebrand Factor. Moreover, the expression of angiogenic genes was compared between equine hydrallantois and age-matched, normal placentas. RESULTS: In the hydrallantoic samples, edema was the main pathological finding. The capillary density was significantly lower in the hydrallantoic samples than in normal placentas. The reduction in the number of vessels was associated with abnormal expression of a subset of angiogenic and hypoxia-associated genes including VEGF, VEGFR1, VEGFR2, ANGPT1, eNOS and HIF1A. We believe that the capillary density and the abnormal expression of angiogenic genes leads to tissue hypoxia (high expression of HIF1A) and edema. Finally, we identified a lower expression of genes associated with steroidogenic enzyme (CYP19A1) and estrogen receptor signaling (ESR2) in the hydrallantoic placenta. DISCUSSION: Based on the presented data, we believe that formation of edema is due to disrupted vascular development (low number of capillaries) and hypoxia in the hydrallantoic placenta. The edema leads to further hypoxia and consequently, causes an increase in vessel permeability which leads to a gradual increase in interstitial fluid accumulation, resulting in an insufficient transplacental exchange rate and accumulation of fluid in the allantoic cavity.
Assuntos
Doenças dos Cavalos , Neovascularização Patológica/patologia , Doenças Placentárias , Placenta/irrigação sanguínea , Poli-Hidrâmnios/patologia , Prenhez , Alantoide/metabolismo , Alantoide/patologia , Animais , Feminino , Doenças dos Cavalos/genética , Doenças dos Cavalos/patologia , Doenças dos Cavalos/fisiopatologia , Cavalos , Densidade Microvascular , Neovascularização Patológica/genética , Neovascularização Patológica/fisiopatologia , Placenta/metabolismo , Placenta/patologia , Placenta/fisiopatologia , Doenças Placentárias/genética , Doenças Placentárias/patologia , Doenças Placentárias/fisiopatologia , Doenças Placentárias/veterinária , Poli-Hidrâmnios/etiologia , Poli-Hidrâmnios/fisiopatologia , Poli-Hidrâmnios/veterinária , Gravidez , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
Biomaterials for tissue engineering include natural and synthetic polymers, but their clinical application is still limited due to various disadvantages associated with the use of these polymers. This uncertainty of the polymeric approach in tissue engineering launches an opportunity to address a key question: can we eliminate the disadvantages of both natural and synthetic polymers by combining them to form a synergistic relationship? To answer this question, we fabricated scaffolds from elastin, collagen, fibrin, and electrospun polycaprolactone (PCL) with different ratios. The material characterization of these scaffolds investigated degradation, water contact angle, angiogenesis by an ex ovo chorion allantoic membrane (CAM) assay, and mechanical and structural properties. Biological activity and specific differentiation pathways (MSC, adipogenic, osteogenic, myogenic, and chondrogenic) were studied by using human adipose-derived stem cells. Results indicated that all composite polymers degraded at a different rate, thus affecting their mechanical integrity. Cell-based assays demonstrated continual proliferative and viable properties of the cells on all seeded scaffolds with the particular initiation of a differentiation pathway among which the PCL/collagen/fibrin composite was the most angiogenic material with maximum vasculature. We were able to tailor the physical and biological properties of PCL-based composites to form a synergistic relationship for various tissue regeneration applications.
