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Results for “Extraembryonic Membranes”

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At least 19 recordsLinked to original sources
PubMed1986

Developmentally regulated expression of the cell-cell adhesion glycoprotein cell-CAM 120/80 in peri-implantation mouse embryos and extraembryonic membranes.

Peri-implantation mouse embryos and extraembryonic membranes were examined immunohistochemically for the expression of the cell-cell adhesion molecule (cell-CAM) 120/80. Cell-CAM 120/80 was seen along the lateral borders of all cells in the blastocyst but became undetectable on trophoblastic giant cells, some mononuclear trophoblastic cells and parietal yolk sac cells when blastocysts were cultured in vitro. In postimplantation embryos in vivo, all parts of the early egg-cylinder reacted with the antibody to cell-CAM 120/80 except for the cells of the parietal endoderm and the primary trophoblastic giant cells. In the late stage egg-cylinder, no cell-CAM 120/80 was seen on the cells of the primitive mesoderm or on the primordial germ cells. The germ cells in genital ridges and fetal gonads remained cell-CAM 120/80-negative throughout the fetal stages of development. In the extraembryonic membranes, the visceral yolk sac, amnion, and the cells of the placental labyrinth were cell-CAM 120/80-positive, whereas, the parietal yolk sac cells and the spongiotrophoblast cells were negative. These data show that cell-CAM 120/80 is found on cells arranged into epithelial layers in the early embryo and extraembryonic tissues, but is not expressed in the dissociated cells differentiating from these epithelia. Thus, the expression of cell-CAM 120/80 appears to be developmentally regulated.

Animals↗
PubMed2003

Histology of the extraembryonic membranes of an oviparous snake: towards a reconstruction of basal squamate patterns.

An understanding of the evolutionary morphology of extraembryonic membranes in reptiles requires information about oviparous as well as viviparous species. We are studying histology and ultrastructure of the extraembryonic membranes of snakes to clarify the evolutionary history of reptilian fetal membranes, including determination of basal (ancestral) ophidian and squamate patterns. Microscopic anatomy of the membranes of oviparous corn snakes (Elaphe guttata) was examined using light and electron microscopy. At mid-development the inner surface of the eggshell is lined by two extraembryonic membranes, the chorioallantois and the omphalallantoic membrane. The chorioallantois consists of a bilayered cuboidal epithelium that overlies the allantoic blood vessels. During development, allantoic capillaries become more abundant, and the chorionic epithelium thins, decreasing the diffusion distance for respiratory gas exchange. The abembryonic pole of the egg is delimited by a bilaminar omphalopleure and isolated yolk mass, the latter of which is lined on its inner face by the allantois. The isolated yolk mass regresses developmentally, and patches of yolk droplets become isolated and surrounded by allantoic blood vessels. By late development, the abembryonic hemisphere has been fully vascularized by allantoic vessels, forming a "secondary chorioallantois." With regard to its extraembryonic membranes, Elaphe gutatta is similar to viviparous snakes. However, this species exhibits features that have not previously been reported among squamates, perhaps reflecting its oviparous reproductive habits. Morphological evidence for the uptake of eggshell material by epithelia of the chorion and omphalopleure suggests that the potential for absorption by extraembryonic membranes predates the origin of viviparity.

Allantois↗
PubMed1993

Monotreme development with particular reference to the extraembryonic membranes.

This paper considers many of the salient features of monotreme development, particularly morphogenesis of the extraembryonic membranes. The uterine endometrium of both monotremes and marsupials exhibits a progesterone driven luteal phase where accelerated utilization of endometrial nutrients is evidenced by a rapid post-primitive streak expansion in the dimensions of the extraembryonic membranes. Monotremes share with marsupials, birds, and reptiles an unspecialized vertebrate mode of genesis of the embryonic disc on the peripheral surface of the yolk-sac. The fused vascularized respiratory chorioallantois is estimated to have a functional life of not more than the terminal 4 to 5 days of the monotreme incubation period. This time interval is of a slightly greater order of magnitude than that found in marsupials with a fused chorioallantois, so far described, but in the context of the proportional elapse of post-primitive streak organogenesis would fall within the marsupial grade. The dominant extraembryonic membrane for nutritive and respiratory function in both monotremes and marsupials is the yolk-sac. This contribution shows that monotremes and marsupials share a much larger suite of developmental anatomical features than previously reported. The evolutionary biologist is confronted with the challenge of how to assign an appropriate weighting to these features as marsupials are considered by many researchers to be allied phylogenetically more closely with eutherian mammals than with monotremes.

Animals↗
PubMed1987

Establishment of a rat placental cell line expressing characteristics of extraembryonic membranes.

A cell line was derived from midgestation chorioallantoic placental explants of the outbred Holtzman rat. The cell line was found to express characteristics of extraembryonic membranes and to grow when introduced into allogeneic hosts. Growth in allogeneic hosts was detected following intraperitoneal injection of the cells but not following subcutaneous injection. The transplanted cells grew as cystic structures free in the peritoneum and as solid masses adhered to various abdominal organs. Cystic structures had a homogeneous morphology consisting of an epithelial-like cell layer surrounding a fluid-filled sac. Solid masses had a heterogeneous morphology, containing parts resembling normal components of the extraembryonic membranes (trophoblast, parietal, and visceral yolk sacs). Biochemical analysis of the placenta-derived cell line and transplanted structures derived from the cell line indicated that the cells had the potential to produce a variety of proteins characteristic of extraembryonic tissues. Cultured cells and both types of in vivo transplants produced the basement membrane protein, laminin. Peritoneal cystic structures also contained alpha-fetoprotein mRNA and very high levels of c-fos mRNA. Solid masses demonstrated elevated alkaline phosphatase activity, a marker of trophoblast cells. Cells grown in vitro expressed elevated c-myc mRNA levels, whereas, c-myc mRNA levels were reduced in the in vivo transplants. The behavior of the cell line in vitro and following in vivo transplantation suggests it contains elements capable of differentiation toward various components of the extraembryonic membranes. The results indicate that the rat placental cell line will be valuable for future studies on the differentiation of trophoblast cells and other components of the extraembryonic membranes.

Alkaline Phosphatase↗
PubMed1993

Expression and cellular localization of retinol-binding protein messenger ribonucleic acid in bovine blastocysts and extraembryonic membranes.

A cDNA clone encoding retinol-binding protein (RBP) was isolated from a bovine conceptus cDNA library by use of an antiserum specific for bovine conceptus RBP (bcRBP). The RBP cDNA clone, designated bcRBP-700, is 732 bp in length and codes for a protein whose predicted amino acid sequence is identical to that of bovine plasma RBP. The size of the RBP mRNA transcript in bovine chorioallantois was approximately 1.4 kb as determined by Northern blot analysis. Expression of the protein and its mRNA in expanding bovine conceptuses (Day 13) and extraembryonic membranes (Day 45) was determined by immunocytochemistry with anti-bcRBP serum and in situ hybridization with 35S-labeled bcRBP-700 cDNA. Strong immunostaining for RBP and hybridization signals for RBP mRNA were observed in trophectoderm of tubular but not spherical Day 13 blastocysts. RBP mRNA was localized in epithelial cells lining the chorion, allantois, and amnion at Day 45 of pregnancy. In addition, RBP mRNA was detected in cotyledons, the sites of chorionic attachment to the uterine endometrium and physiological exchange between the embryo and its mother. Expression of RBP in expanding conceptuses, developing extraembryonic membranes, and sites of fetal-maternal attachment suggests that the extraembryonic membranes regulate retinol transport and availability within the conceptus.

Allantois↗
PubMed1995

Analysis of messenger ribonucleic acid and protein for the ligands and receptors of the platelet-derived growth factor signaling pathway in the placenta, extraembryonic membranes, and uterus during the latter half of murine gestation.

Previous investigation of ligand and receptor messenger RNA (mRNA) expression implicated the platelet-derived growth factor (PDGF) pathway as a participant in the maintenance of pregnancy and fetal development during the first half of murine gestation. We extended these studies using Northern and in situ RNA hybridization and immunohistochemical detection of protein to evaluate the expression kinetics and cell-specific localization of PDGF-A, PDGF-B, PDGF alpha-receptor, and PDGF beta-receptor in mouse placenta, extraembryonic membranes, and uterus during the second half of gestation (days 9.5-18.5). Northern blotting experiments reveal that mRNAs for the PDGF signaling components exhibit unique time-dependent and tissue-specific expression in the placenta and uterus, being progressively and coordinately up-regulated as gestation proceeds. Cell-specific localization of mRNA and protein by in situ hybridization and immunohistochemistry demonstrates widespread expression in multiple cell types of the placenta, gravid uterus, and extraembryonic membranes. Abundant PDGF protein and mRNA expression is exhibited in the nucleated fetal erythroid progenitor cells that originate in the extraembryonic membranes and circulate throughout the developing conceptus. Our data together with those of previous studies demonstrate that PDGF ligands and receptors are globally expressed in many cell types within fetal and maternal tissues during murine gestation and, thus, imply a potential role for PDGF in fetal development and maternal-fetal interactions.

Animals↗
PubMed1979

Paternal X chromosome expression in extraembryonic membranes of XO mice.

The paternally derived allelic form of the X chromosome linked enzyme phosphoglycerate kinase (PGK-1) is expressed in both the fetus and extraembryonic membranes of 9.5 day post coitum XO (XpO) mouse conceptuses. Previous studies on trophectoderm and primitive endoderm derived extraembryonic membranes in XX conceptuses suggest expression of only the maternally derived X chromosome (Xm). Our results suggest that the observed lack of expression of Xp in the trophectoderm and primitive endoderm derivatives of XX embryos is not an intrinsic property of the Xp chromosome.

Alleles↗
PubMed1986

Insulin receptors in embryo and extraembryonic membranes of early somite rat conceptus.

Intact rat conceptuses were cultured from day 9.5 of gestation on. Individual components of the conceptus, including the embryo and the extraembryonic membranes (consisting of yolk sac, amnion, and allantoic placenta), were isolated and examined for insulin receptors at two time points during organogenesis: day 10.4 of gestation (approximately 10-12 somites) when the yolk sac had become vascularized and just before closure of the anterior neuropore and day 11.6 (approximately 27-31 somites) when vascularization of the chorioallantoic placenta had been established and the neural tube was closed completely. The studies were designed to provide inferential insights about the possible role of insulin in embryogenesis during different phases of nutrient delivery. Active insulin degradation occurred with embryo as well as membrane homogenates during incubation at 37 degrees C. Degradation was markedly reduced at 4 degrees C, and binding of 125I-labeled insulin by embryo or membrane homogenates prepared on day 10.4 or 11.6, respectively, of gestation approached equilibrium after a 20-h incubation at this temperature. Values for the specific binding of tracer (0.4 ng/ml) or carrier (10.4 ng/ml) insulin by embryo and membrane homogenates were the same on days 10.4 and 11.6; specific binding was significantly greater with preparations of membranes than embryo at both time points. Full binding curves on day 11.6 showed similar affinities for insulin by embryo and membranes (Ke = 1.2 X 10(8)/M and 4.6 X 10(8)/M, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Allantois↗
PubMed1998

Formation of the placenta and extraembryonic membranes.

In eutherian mammals, the first cell types that are specified during embryogenesis are committed to form extraembryonic (placenta and fetal membranes) rather than embryonic structures. The trophoblast cell lineage, for example, forms at the morula-to-blastocyst transition: cells at the periphery of the morula become trophoblast, whereas cells on the inside remain undifferentiated embryonic ectoderm, which later gives rise to the fetus as well as the endodermal and mesodermal components of the placenta and extraembryonic membranes. Genetic studies in mice are beginning to identify growth factors and cell adhesion molecules that mediate interactions between cell types that are essential for morphogenesis of the placenta and fetal membranes, as well as transcription factors that control the differentiation of extraembryonic cell types.

Animals↗
PubMed1993

Expression of CD59, a human complement system regulatory protein, in extraembryonic membranes.

CD59 (leukocyte cluster of differentiation antigen 59), is a phosphatidylinositol glycan-anchored membrane protein that inhibits lysis of cells by terminal complement system components. To further define complement regulatory proteins relevant to pregnancy, this study characterized the expression of CD59 in human extraembryonic membranes. Immunohistology with CD59 monoclonal antibody MEM-43 showed that this molecule was normally present on the apical surface of the syncytiotrophoblast, on extravillous cytotrophoblast, and amniotic epithelium. Immunoblotting confirmed that first and second trimester syncytiotrophoblast microvilli (STM) contained a glycoprotein similar in mass and glycosylation to CD59 from adult cells and tissues. Reactivities of STM with MEM-43 in ELISA were 2- to 6-fold higher than those of kidney, erythrocyte and platelet membranes. Term placental STM from recurrent spontaneous aborting patients after immunotherapy, reacted with MEM-43 in ELISA similarly to STM from normal individuals. Plasmas from pregnant women and umbilical cords had 50% or greater reactivity with MEM-43 than did normal plasmas. CD59 could help protect extraembryonic epithelia from damage by complement in maternal blood and amniotic fluid. The apical location of CD59 reflects the immunological roles and functional polarization of plasma membranes in the syncytiotrophoblast.

Abortion, Spontaneous↗
PubMed1995

Expression of the novel basic helix-loop-helix gene eHAND in neural crest derivatives and extraembryonic membranes during mouse development.

We employed the yeast two-hybrid technique to screen a mouse embryo cDNA library for novel tissue-specific Class B basic helix-loop-helix (bHLH) transcription factors, which heterodimerize with the ubiquitously expressed Class A bHLH protein E12. From this screen, we cloned a novel bHLH protein, which we named eHAND. Its low sequence identity with other bHLH family members and unique expression pattern during development suggest that eHAND defines a new subclass of Class B bHLH proteins. eHAND was expressed at high levels in trophoblast cells and extraembryonic membranes throughout development. The first site of eHAND expression in embryos was the heart, where it was expressed at high levels between 8.5 and 10.5 days post coitum (d.p.c.), after which transcript levels declined abruptly. By 13.5 d.p.c., eHAND expression in the heart was localized to regions of valve formation. Expression in other regions of the embryo was confined to tissues with a substantial neural crest component. eHAND was expressed in the first branchial arch and its derivatives, in the sympathoadrenal lineage, and in the enteric systems. The expression pattern of eHAND during development is distinct from that of other bHLH genes and suggests that it has a role in formation of extraembryonic tissues, heart, and neural crest derivatives.

Amino Acid Sequence↗