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PubMed1997

Regulation of conceptus development and attachment in pigs.

Implantation/placentation in domestic pigs is preceded by synthesis of oestrogen by the conceptus to maintain functional corpora lutea throughout pregnancy and a rapid morphological transformation of conceptuses from spherical to long filamentous thread-like structures. Initial conceptus expansion, reaching a metre in length, not only delineates the surface area for placental attachment, but also provides the mechanism for delivery of oestrogen to signal events necessary for placentation throughout the uterine horn. Timing for conceptus gene expression to induce trophoblast expansion and attachment in pigs is temporally associated with downregulation of progesterone receptors and increase in oestrogen receptors within the uterine epithelium. Within the confines of the uterine lumen, pig conceptuses normally do not erode or invade through the uterine epithelial surface. However, the pig conceptus possesses extensive proteolytic activity as it is highly invasive outside the uterine lumen of the pig. Initial release of oestrogen by the elongating pig conceptus induces endometrial release of cytokines and a variety of protease inhibitors. Recently, endometrial expression for the inter-trypsin inhibitor (I alpha I) family of protease inhibitors has been detected in the pig endometrium during conceptus elongation and attachment. It is possible that I alpha Is may function to inhibit trophoblast invasion and also serve as targets for adhesion molecules, such as integrins and heparin, to aid in placental attachment to the uterine epithelium.

Animals↗
PubMed2004

Induction and improved embryonic development by the nucleus of Pander in associated avian blastoderm parts: influence of delta or gamma ooplasm.

After placing in vitro, central subgerminal ooplasm (containing a central nucleus of Pander) from a quail germ disc of a prelaid egg (before symmetrization) on the upper layer of an isolated chicken antisickle, we observed the induction of a radially oriented preneural plate (without interference of chordamesoblast). This observation suggests the primary existence during the period of symmetrization in utero of an until now unknown temporospatially linked "vertical" effect, emanating from the nucleus of Pander, on the parallel (pre)neural plate anlage forming part of the area centralis in the overlying blastoderm. For comparison, we "sandwiched" in vitro a quail sickle endoblast fragment between the deep side of the upper layer of an isolated chicken antisickle region and a central subgerminal ooplasmic mass. This resulted in a colonization of the subgerminal ooplasmic mass by quail sickle endoblast cells followed by improved neurulation and/or gastrulation phenomena. The latter never occurs in the absence of central subgerminal ooplasm. In both types of experiments there seems to exist a common link between the observed induction phenomena: the presence of delta ooplasm in the involved deep structures. Indeed, the nucleus of Pander contains delta ooplasm as well as the structures derived from it, i.e., endophyll with primordial germ cells and sickle endoblast-derived cells after colonization of the neighboring central ooplasm (present study). Therefore, we think that the preneural plate-inducing effect observed after placing a nucleus of Pander on the antisickle region is due to the presence of a factor in the delta ooplasm that diffuses in the neighborhood. The appearance of gastrulation phenomena in the second type of experiment seems to be due to colonization of the more peripheral part of the central subgerminal ooplasm containing the more superficial and peripheral gamma ooplasm in which Rauber's sickle material can develop. This suggests that the kind of involved ooplasm (delta or gamma) can predetermine the inductive activity of the deep structures that contain it: the central part of the nucleus of Pander and/or endophyll for preneurulation phenomena and sickle endoblast (in the presence of central subgerminal ooplasm) for gastrulation and/or neurulation phenomena.

Animals↗
PubMed1990

Distribution and functional role of laminin during induction of the embryonic axis in the chick embryo.

Laminin is a major glycoprotein of basement membranes and has been shown to promote cell adhesion, and movement of various nonepithelial cells and tumour cells. Using antibodies to laminin in paraffin sections and cultured embryos, we have studied the distribution of laminin and its involvement in the first morphogenetic events, beginning with the first extensive cellular migrations and interactions that result in the induction of the primitive streak (PS) and of the neural plate in the early chick embryo. Laminin immunogold labeling was not detected in the blastoderm at stage X. At stage XIII, laminin immunoreactivity was detected at the ventral surface of the epiblast and in the entire hypoblast. The intense labeling of the hypoblast indicated that these cells are active in laminin synthesis. Extracellular matrix (ECM) started accumulating as the first embryonic spaces were forming, before the morphogenetic movements of gastrulation were initiated. Immunogold labeling revealed a punctate pattern of laminin distribution in the ECM in the blastocoele, and in the space below the neural plate. Laminin, which is a multidomain molecule known to interact with other molecules of the ECM and with the cell surface, could serve as the scaffold for highly specific contact points of migrating cells and for the folding of epithelial sheets during this time in the developing embryo. We incubated blastoderms at stages X and XIII with laminin antibodies (1:30 dilution) for 4 h, then cultured the blastoderms further in plain egg albumin. The laminin antibodies did not interfere with triggering of PS cell movements, but perturbed the normal migration pattern of these cells. A normal PS did not form and, as a consequence, the embryonic axis was not induced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Inductive interactions and embryonic equivalence groups in a basal metazoan, the ctenophore Mnemiopsis leidyi.

Ctenophores undergo locomotion via the metachronal beating of eight longitudinally arrayed rows of comb plate cilia. These cilia are normally derived from two embryonic lineages, which include both daughters of the four e1 micromeres (e11 and e12) and a single daughter of the four m1 micromeres (the m12 micromeres). Although the e1 lineage is established autonomously, the m1 lineage requires an inductive interaction from the e1 lineage to contribute to comb plate formation. Successive removal of the e1 progeny at later stages of development indicates that this interaction takes place after the 32-cell stage and likely proceeds over a prolonged period of development. Normally, the e1, cell lies in closest proximity to the m12 cell that generates comb plate cilia; however, either of the e1 daughters (e11 or e12) is capable of emitting the signal required for m1 descendants to form comb plates. Previous cell lineage analyses indicate that the two e1 daughters generate the same suite of cell fates. On the other hand, the m1 daughters (m11 and m12) normally give rise to different cell fates. Reciprocal m1 daughter deletions show that in the absence of one daughter, the other cell can generate all the cell types normally formed by the missing cell. Together, these findings demonstrate that the two m1 daughters (m11 and m12) represent an embryonic equivalence group or field and that differences in the fates of the two m1 daughters are normally controlled by cell-cell interactions. These combined properties of ctenophore development, including the utilization of deterministic cleavage divisions, inductive interactions, and the establishment of embryonic fields or equivalence groups, are remarkably similar to those present in the development of various bilaterian metazoans.

Animals↗
PubMed2006

Gli3-mediated somitic Fgf10 expression gradients are required for the induction and patterning of mammary epithelium along the embryonic axes.

Little is known about the regulation of cell fate decisions that lead to the formation of five pairs of mammary placodes in the surface ectoderm of the mouse embryo. We have previously shown that fibroblast growth factor 10 (FGF10) is required for the formation of mammary placodes 1, 2, 3 and 5. Here, we have found that Fgf10 is expressed only in the somites underlying placodes 2 and 3, in gradients across and within these somites. To test whether somitic FGF10 is required for the formation of these two placodes, we analyzed a number of mutants with different perturbations of somitic Fgf10 gradients for the presence of WNT signals and ectodermal multilayering, markers for mammary line and placode formation. The mammary line is displaced dorsally, and formation of placode 3 is impaired in Pax3ILZ/ILZ mutants, which do not form ventral somitic buds. Mammary line formation is impaired and placode 3 is absent in Gli3Xt-J/Xt-J and hypomorphic Fgf10 mutants, in which the somitic Fgf10 gradient is shortened dorsally and less overall Fgf10 is expressed, respectively. Recombinant FGF10 rescued mammogenesis in Fgf10(-/-) and Gli3Xt-J/Xt-J flanks. We correlate increasing levels of somitic FGF10 with progressive maturation of the surface ectoderm, and show that full expression of somitic Fgf10, co-regulated by GLI3, is required for the anteroposterior pattern in which the flank ectoderm acquires a mammary epithelial identity. We propose that the intra-somitic Fgf10 gradient, together with ventral elongation of the somites, determines the correct dorsoventral position of mammary epithelium along the flank.

Animals↗
PubMed1990

Cartilage, bone and tooth induction during early embryonic mouse mandibular morphogenesis using serumless, chemically-defined medium.

Studies were designed to test the hypothesis that plasma- and serum-deprived embryonic cells and tissues in vitro are capable of producing growth regulating factors which augment cartilage, bone and tooth induction during mouse mandibular process development. Embryonic mouse first branchial arch-derived mandibular processes (E11-E12, Theiler stages 18-19) or cap stage molar tooth (M1) organs (E15-E16, Theiler stage 23) expressed morphogenesis, histogenesis and cytodifferentiation (e.g., Meckel's cartilage and mandibular bone) when cultured as explants in permissive serumless and chemically-defined BGJB medium for periods up to 31 days in vitro. Organ cultures of early mandibular process explants in serumless conditions showed DNA synthesis comparable to the time- and position-restricted patterns characteristic for control in vivo development. As a paradigm for embryonic cell expression of putative growth factors, sense and antisense oligodeoxynucleotide probes corresponding to amino acids 1070-1081 for preproEGF, and antibodies directed against amino acids 348-691 of preproEGF, were used to identify and localize mRNA transcripts and translation products. Our preliminary evidence suggests that odontogenic epithelial and ectomesenchyme cells produce EGF-like products during instructive phases of tooth development. We suggest that plasma- and serum-deprived cells and tissues in vitro produce autocrine and/or paracrine growth factors which mediate embryonic mandibular morphogenesis, histogenesis and cytodifferentiation.

Animals↗
PubMed1996

Induction and differentiation of extra-embryonic mesoderm in the mouse.

Extra-embryonic mesoderm, derived at the time of gastrulation from the primitive streak, gives rise to several tissues that function to provide the embryo with nutrients, a means of waste disposal, and mechanical protection. Little is known about the differentiation of this tissue and about the growth and transcription factors involved. The present review focussed on growth and transcription factors that may be involved in differentiation of extra-embryonic mesoderm, and results from fate-mapping and transplantation studies. Methods in vitro available for assaying the effects of growth and transcription factors on development of extra-embryonic development are also discussed.

Animals↗
PubMed2001

Spalt modifies EGFR-mediated induction of chordotonal precursors in the embryonic PNS of Drosophila promoting the development of oenocytes.

Genes of the spalt family encode nuclear zinc finger proteins. In Drosophila melanogaster, they are necessary for the establishment of head/trunk identity, correct tracheal migration and patterning of the wing imaginal disc. Spalt proteins display a predominant pattern of expression in the nervous system, not only in Drosophila but also in species of fish, mouse, frog and human, suggesting an evolutionarily conserved role for these proteins in nervous system development. Here we show that Spalt works as a cell fate switch between two EGFR-induced cell types, the oenocytes and the precursors of the pentascolopodial organ in the embryonic peripheral nervous system. We show that removal of spalt increases the number of scolopodia, as a result of extra secondary recruitment of precursor cells at the expense of the oenocytes. In addition, the absence of spalt causes defects in the normal migration of the pentascolopodial organ. The dual function of spalt in the development of this organ, recruitment of precursors and migration, is reminiscent of its role in tracheal formation and of the role of a spalt homologue, sem-4, in the Caenorhabditis elegans nervous system.

Animals↗
PubMed1983

Increase during passage in culture in susceptibility of Syrian hamster embryonic cells to induction of chromosome aberrations by 7,12-dimethylbenz(a)-anthracene.

Studies were made on chromosome aberrations in Syrian hamster embryonal fibroblasts (SHEF) at early and late passages in culture. Aberrations were induced with a potent indirect clastogen, 7,12-dimethylbenz(a)anthracene (DMBA). Results showed that cells at late passages were much more susceptible to this chemical than cells at early passages: the frequency of aberrant metaphases was usually less than 20% at the 2nd passage, but it gradually increased with increase in the number of culture passages, reaching 50% or more at the 8th passage in one experiment and 6th-7th passage in another. Induction of chromosome aberrations was also examined in V79 cells co-cultured with hamster cells at early and late passages. V79 cells are known to have no drug-metabolizing enzyme activity. Results demonstrate that the frequency of chromosome aberrations of V79 cells was much greater in the presence of hamster cells at late passages than in the presence of cells at early passages.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

Angiogenesis induction by tumors, embryonic tissues, and lymphocytes.

Although it is well established that tumors can induce endothelial cell mitosis and angiogenesis leading to extensive neovascularization, little is known concerning the spectrum of normal cells or tissues that may have similar inductive capabilities. A variety of developmentally active tissues were tested: mouse embryonic organ rudiments, mouse and rabbit trophoblast and placenta, and blastemal fragments obtained from regnerating deer antlers. Assays for angiogenesis included grafts made to the chorioallantoic membrane of chick embryos and grafts placed intracorneally in adult rabbit eyes. Virtually all of these test tissues were negative, the only exceptions being some antler grafts and some grafts obtained from metanephric tubules of the embryonic mouse kidney.

Angiogenesis Inducing Agents↗
PubMed1983

Epithelial induction of osteogenesis in embryonic chick mandibular mesenchyme: a possible role for basal lamina.

The initiation of osteogenesis at 7 days in the embryonic chick mandibular mesenchyme depends on an epithelial induction in the mandible to day 4. This article reviews a series of experiments conducted to study the nature of this inductive mechanism. Transfilter tissue recombinations were used to determine whether direct tissue apposition was required for induction. Ultrastructural studies of the epithelial-mesenchymal interface were conducted to see if direct epithelial-mesenchymal cell-cell contacts occurred during the inductive stage in vivo. Epithelial cells were cultured on Millipore filters for 28 days and allowed to deposit extracellular products. These products were tested for inductive activity. Findings from these three sets of experiments were discussed with respect to the inductive mechanism. Our results indicate that the induction is not mediated by a diffusible substance and that direct apposition of the two tissues is required. The mechanism of induction, however, does not require direct epithelial-mesenchymal cell to cell contacts. This suggests that a nondiffusible component of the extracellular matrix may be involved. Epithelial extracellular products are inductively active and have the appearance of basal lamina. The active component of the extracellular product is proteinaceous, perhaps collagen, and appears to be situated in the epithelial basal lamina. The role of basal lamina in epithelial-mesenchymal interactions is discussed.

Animals↗
PubMed1993

Retinoic acid induction of major histocompatibility complex class I genes in NTera-2 embryonal carcinoma cells involves induction of NF-kappa B (p50-p65) and retinoic acid receptor beta-retinoid X receptor beta heterodimers.

Retinoic acid (RA) treatment of human embryonal carcinoma (EC) NTera-2 (NT2) cells induces expression of major histocompatibility complex (MHC) class I and beta-2 microglobulin surface molecules. We found that this induction was accompanied by increased levels of MHC class I mRNA, which was attributable to the activation of the two conserved upstream enhancers, region I (NF-kappa B like) and region II. This activation coincided with the induction of nuclear factor binding activities specific for the two enhancers. Region I binding activity was not present in undifferentiated NT2 cells, but binding of an NF-kappa B heterodimer, p50-p65, was induced following RA treatment. The p50-p65 heterodimer was produced as a result of de novo induction of p50 and p65 mRNAs. Region II binding activity was present in undifferentiated cells at low levels but was greatly augmented by RA treatment because of activation of a nuclear hormone receptor heterodimer composed of the retinoid X receptor (RXR beta) and the RA receptor (RAR beta). The RXR beta-RAR beta heterodimer also bound RA responsive elements present in other genes which are likely to be involved in RA triggering of EC cell differentiation. Furthermore, transfection of p50 and p65 into undifferentiated NT2 cells synergistically activated region I-dependent MHC class I reporter activity. A similar increase in MHC class I reporter activity was demonstrated by cotransfection of RXR beta and RAR beta. These data show that following RA treatment, heterodimers of two transcription factor families are induced to bind to the MHC enhancers, which at least partly accounts for RA induction of MHC class I expression in NT2 EC cells.

Animals↗
PubMed2003

Induction of an embryonic globin gene promoter by short-chain fatty acids.

Short-chain fatty acids (SCFAs) and dimethyl sulfoxide (DMSO) induce adult erythroid differentiation in murine erythroleukemia (MEL) cells, but only SCFAs concurrently up-regulate expression from the endogenous embryonic globin gene epsilony. The epsilony promoter, linked to a reporter gene and stably transfected into MEL cells, was tested during adult erythroid differentiation. Both the epsilony-CACCC site at -114 bp and enhancer sequences (hypersensitive site 2 [HS2]) from the beta-globin locus control region (LCR) were essential to maximal SCFA-mediated induction of expression from these constructs in MEL cells. Gel-shift analyses of binding activity from SCFA-induced MEL cell nuclear extracts showed in vitro binding by specificity proteins 1 and 3 (SP1, SP3) and basic or erythroid Krüppel-like factors (BKLF, EKLF) at the epsilony-CACCC site. In a functional analysis, transient cotransfections in nonerythroid NIH/3T3 cells of SP1, SP3, BKLF, or EKLF and HS2 epsilony promoter-luciferase constructs, with or without coactivators (p300, CREB-binding protein [CBP], or p300/CBP-associated factor [PCAF]) and SCFAs, were performed. SP1, SP3, and EKLF further increased expression from HS2 epsilony promoter constructs following exposure to SCFAs. This effect was variably augmented by coactivators and was diminished in EKLF mutants that were unable to undergo histone/factor-acetyl transferase (H/FAT)-mediated acetylation. In addition, acetylation of SP1 was detectable in NIH/3T3 cells following exposure to SCFAs. In sum, LCR sequence and an embryonic globin gene promoter CACCC site were essential to that promoter's up-regulation during SCFA-mediated induction of adult erythroid differentiation in vitro. Of factors that interact at the CACCC site, SCFA-mediated acetylation is implicated in SP1 and EKLF, and may be a mechanism through which SCFAs induce embryonic/fetal globin gene promoters during adult erythroid differentiation.

Acetylation↗
PubMed1978

Effect of various sugars on the induction of chick embryonic intestinal disaccharidases in the organ culture system.

Disaccharidases activities in 20-day-old chick embryonic intestine were induced by the addition of sucrose, maltose, fructose and glucose to the culture medium. However, maltitol, which cannot be digested by intestinal enzymes, showed no effect on the induction of disaccharidase activity. Kinetic study of the enzymes demonstrated that the maximum velocity (Vmax) and the Michaelis constant (Km) of sucrose induced disaccharidases activities of the explants showed changes similar to those observed in the chick of same developmental stage in vivo. Namely, Vmax values of sucrase and maltase were increased. Km values of sucrase did not change, but that of maltase showed a significant decrease during development.

Animals↗
PubMed2001

New approach for the establishment of mouse early embryonic stem cells and induction of their differentiation.

Eleven early embryonic stem (EES) cell lines were established using a new novel method. Two cell stage embryos from the ddY mouse strain were cultured in alpha-MEM supplemented with 10% fetal calf serum (FCS) and embryotrophic factors (ETFs) and allowed to develop to the trilaminal germ disc embryonic stage. Only small round cells (EES cells) were isolated by the colony isolating technique and subsequently cultured in the same medium containing the ETFs and leukemia inhibitory factors (LIF-10 ng/ml). The newly established embryonic stem (ES) cells isolated from inner cell mass of blastocysts differentiated from two cell stage embryo in culture. The EES and ES cell lines were maintained in an undifferentiated state using Ham's F12 medium supplemented with 10% FCS and 1 ng/ml of LIF. The EES cells maintained their normal genetic and morphological features as well as their potential to differentiate into a broad spectrum of cell types as well as their ability to contribute to all cell lineages in chimeric mice. Moreover, these cell lines changed and differentiated into various kinds of cells by removing LIF and by the addition of ETFs to the vitro culture system. All 11 EES cell lines and 3 ES cell lines formed embryoid bodies; however, cell line EES-4 formed tube-like structures which extended, anastomosed with each other, and finally formed networks when the LIF were absent. Primitive germ organ-like structures composed of 3 germ layers were recognized in the cultures following the administration of ETFs. In conclusion, the new method devised by us is a novel, easy and reliable technique for establishing EES cell lines.

Animals↗
PubMed1998

Cell lineages in the embryonic kidney: their inductive interactions and signalling molecules.

The first signalling genes acting in the inductive interactions in the kidney have now been identified. Differentiation of the permanent kidney or the metanephros is critically dependent on inductive signalling between the nephrogenic mesenchyme and ureteric bud epithelium. Further inductive interactions occur between developing nephrons, interstitial stroma, endothelial cells and neurones. Glial-cell-line-derived neurotrophic factor is a signal for the ureteric bud initiation and branching, and Wnt4 is an autocrine epithelializing signal at the pretubular stage of nephron formation. The signals for renal angiogenesis and innervation are less well defined, but seem to include vascular endothelial growth factor and neurotrophins, at least. The ureteric-bud-derived signal for induction of the nephrogenic mesenchyme (to bring the cells to the condensate stage) is not yet known, but fibroblast growth factor 2 is a good candidate. None of the signalling genes identified from the embryonic kidney is specific to the organ, which raises some general questions. How do the organs develop from similar rudiments to various patterns with different cell types and functions? Does the information for organ-specific differentiation pathways retain in the epithelial or mesenchymal compartment? The present, rather fragmentary molecular data would favour the view that similar molecules acting in different combinations and developmental sequences, rather than few organ-specific master genes, could be responsible for the divergence of patterning.

Animals↗
PubMed2006

Mouse endosialin, a C-type lectin-like cell surface receptor: expression during embryonic development and induction in experimental cancer neoangiogenesis.

Endosialin is a C-type lectin-like cell surface receptor of unknown function, with a distinctive pattern of endothelial expression in newly formed blood vessels in human cancers. The murine orthologue of endosialin has been identified, opening up the analysis of developmental regulation in the embryo and in aberrant tissue remodeling, notably cancer angiogenesis. To advance these studies we have generated an antibody to the extracellular domain of mouse endosialin and mapped protein expression from embryonic day E10.0 to the adult stage, complemented by mRNA quantification and co-typing for standard endothelial markers. Four main findings emerged. First, endosialin protein is restricted to vascular endothelium and fibroblast-like cells in developing organs, and largely disappears in the adult. Second, endothelial expression varies markedly between organs regarding spatial and temporal patterns. For instance, in the E10.0 embryo, endosialin is prominent in the endothelium of the dorsal aorta and, from E11.0 to E14.5, in vessels sprouting from the dorsal aorta, in perineural vascular plexuses, and in brain capillaries. Third, circumscribed mesenchymal expression in fibroblast-like cells was evident throughout development, most pronounced adjacent to certain budding epithelia, as exemplified by the lung and kidney glomeruli, but unrelated to the endothelial expression. The endosialin protein persists in the stromal fibroblasts of the adult uterus. Finally, in subcutaneous cancer xenograft models endosialin re-appears in the host-derived tumor stroma, both in neo-angiogenic vascular endothelium and in activated stromal fibroblasts. In future studies, the search for intrinsic or extrinsic signals contributing to endosialin induction in cancer stroma will be of interest.

Animals↗