17 results on '"Markwald, R. R"'
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2. Introduction to the special issue "the enteric nervous system and its targets"
- Author
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Timmermans JP, Markwald RR, and Litke LL
- Published
- 2001
- Full Text
- View/download PDF
3. Conotruncal anomalies in the trisomy 16 mouse: an immunohistochemical analysis with emphasis on the involvement of the neural crest.
- Author
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Waller BR 3rd, McQuinn T, Phelps AL, Markwald RR, Lo CW, Thompson RP, and Wessels A
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- Animals, Connexin 43 analysis, DiGeorge Syndrome embryology, DiGeorge Syndrome etiology, DiGeorge Syndrome pathology, Disease Models, Animal, Down Syndrome etiology, Down Syndrome pathology, Female, Fluorescent Antibody Technique, Indirect, Heart Defects, Congenital etiology, Heart Defects, Congenital pathology, Heart Ventricles abnormalities, Karyotyping, Male, Mice, Mice, Inbred C57BL, Mice, Mutant Strains, Neural Crest chemistry, Neural Crest pathology, Pregnancy, Yolk Sac cytology, Heart Defects, Congenital embryology, Neural Crest abnormalities, Trisomy
- Abstract
The trisomy 16 (Ts16) mouse is generally considered a model for human Down's syndrome (trisomy 21). However, many of the cardiac defects in the Ts16 mouse do not reflect the heart malformations seen in patients suffering from this chromosomal disorder. In this study we describe the conotruncal malformations in mice with trisomy 16. The development of the outflow tract was immunohistochemically studied in serially sectioned hearts from 34 normal and 26 Ts16 mouse embryos ranging from 8.5 to 14.5 embryonic days. Conotruncal malformations observed in the Ts 16 embryos included double outlet right ventricle, persistent truncus arteriosus, Tetralogy of Fallot, and right-sided aortic arch. This spectrum of malformations is remarkably similar to that seen in humans suffering from DiGeorge syndrome (DGS). As perturbation of neural crest development has been proposed in the pathogenesis of DGS we specifically focussed on the fate of neural crest derived cells during outflow tract development of the Ts16 mouse using an antibody that enabled us to trace these cells during development. Severe perturbation of the neural crest-derived cell population was observed in each trisomic specimen. The abnormalities pertained to: 1) the size of the columns of neural crest-derived cells (or prongs); 2) the spatial orientation of these prongs within the mesenchymal tissues of the outflow tract; and 3) the location in which the neural crest cells interact with the myocardium. The latter abnormality appeared to be responsible for ectopic myocardialization found in trisomic embryos. Our observations strongly suggest that abnormal neural crest cell behavior is involved in the pathogenesis of the conotruncal malformations in the Ts16 mouse., (Copyright 2000 Wiley-Liss, Inc.)
- Published
- 2000
- Full Text
- View/download PDF
4. Atrial development in the human heart: an immunohistochemical study with emphasis on the role of mesenchymal tissues.
- Author
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Wessels A, Anderson RH, Markwald RR, Webb S, Brown NA, Viragh S, Moorman AF, and Lamers WH
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- Antibodies, Monoclonal, Creatine Kinase metabolism, Embryo, Mammalian enzymology, Heart Atria enzymology, Humans, Immunoenzyme Techniques, Isoenzymes, Mesoderm enzymology, Myocardium enzymology, Pulmonary Veins embryology, Embryo, Mammalian embryology, Heart Atria embryology, Mesoderm cytology
- Abstract
The development of the atrial chambers in the human heart was investigated immunohistochemically using a set of previously described antibodies. This set included the monoclonal antibody 249-9G9, which enabled us to discriminate the endocardial cushion-derived mesenchymal tissues from those derived from extracardiac splanchnic mesoderm, and a monoclonal antibody recognizing the B isoform of creatine kinase, which allowed us to distinguish the right atrial myocardium from the left. The expression patterns obtained with these antibodies, combined with additional histological information derived from the serial sections, permitted us to describe in detail the morphogenetic events involved in the development of the primary atrial septum (septum primum) and the pulmonary vein in human embryos from Carnegie stage 14 onward. The level of expression of creatine kinase B (CK-B) was found to be consistently higher in the left atrial myocardium than in the right, with a sharp boundary between high and low expression located between the primary septum and the left venous valve indicating that the primary septum is part of the left atrial gene-expression domain. This expression pattern of CK-B is reminiscent of that of the homeobox gene Pitx2, which has recently been shown to be important for atrial septation in the mouse. This study also demonstrates a poorly appreciated role of the dorsal mesocardium in cardiac development. From the earliest stage investigated onward, the mesenchyme of the dorsal mesocardium protrudes into the dorsal wall of the primary atrial segment. This dorsal mesenchymal protrusion is continuous with a mesenchymal cap on the leading edge of the primary atrial septum. Neither the mesenchymal tissues of the dorsal protrusion nor the mesenchymal cap on the edge of the primary septum expressed the endocardial tissue antigen recognized by 249-9G9 at any of the stages investigated. The developing pulmonary vein uses the dorsal mesocardium as a conduit to reach the primary atrial segment. Initially, the pulmonary pit, which will becomes the portal of entry for the pulmonary vein, is located along the midline, flanked by two myocardial ridges. As development progresses, tissue remodeling results in the incorporation of the portal of entry of the pulmonary vein in left atrial myocardium, which is recognized because of its high level of creatine. Closure of the primary atrial foramen by the primary atrial septum occurs as a consequence of the fusion of these mesenchymal structures., (Copyright 2000 Wiley-Liss, Inc.)
- Published
- 2000
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5. Origin of the pulmonary venous orifice in the mouse and its relation to the morphogenesis of the sinus venosus, extracardiac mesenchyme (spina vestibuli), and atrium.
- Author
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Tasaka H, Krug EL, and Markwald RR
- Subjects
- Animals, Embryonic and Fetal Development, Heart Atria, Heart embryology, Mesoderm physiology, Mice embryology, Pulmonary Veins embryology
- Abstract
Background: Human embryology textbooks indicate that the trunks of the pulmonary vein and artery originate from the left atrium and aortic sac, respectively, based on histological analyses of limited human specimens. However, our studies show that the pulmonary venous trunk in the mouse as in other nonhuman vertebrates originates from a vascular "sac" at the venous pole, the sinus venosus., Methods: Mouse embryos of 9-11 days gestation were obtained and staged according to Theiler's criteria and fixed in Carnoy's solution. Samples were embedded in paraffin and serial sections were prepared., Results: Histological analysis showed that at day 9.5 the pulmonary venous rudiment was initially observed along the left margin in the extracardiac mesenchyme that separated the venous pole of the heart from the lung buds. The endothelium of the pulmonary vein was continuous, with a vascular sac we identified as sinus venosus based on its location immediately posterior to the left sinoatrial fold. The sinus venosus became incorporated into the left atrium (days 10-10.5) to form part of the posterior atrial wall. Similarly, the pulmonary vein and associated extracardiac mesenchyme were "drawn" into the atrium. This extracardiac mesenchyme of the venous pole, also called "spina vestibuli" and containing the pulmonary vein at its left margin, formed a wedge-shaped invagination within the atrium that contributed nonmuscular tissue to the primary atrial septum., Conclusions: We propose that the orifice of the pulmonary vein establishes a link with the left side of the atrium as a consequence of a venous sac, the sinus venosus, and its associated mesenchyme (in which the root of the pulmonary vein is embedded) being incorporated into the atrium.
- Published
- 1996
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6. Multiple glycoproteins localize to a particulate form of extracellular matrix in regions of the embryonic heart where endothelial cells transform into mesenchyme.
- Author
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Sinning AR, Krug EL, and Markwald RR
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- Animals, Cell Differentiation physiology, Cell Membrane physiology, Cell Membrane ultrastructure, Chick Embryo, Chromatography, Affinity, Edetic Acid, Endothelium, Vascular physiology, Fibronectins analysis, Immunohistochemistry methods, Lectins, Mesoderm physiology, Endothelium, Vascular cytology, Extracellular Matrix chemistry, Glycoproteins analysis, Heart embryology, Mesoderm cytology, Myocardium chemistry, Myocardium cytology, Plant Lectins, Soybean Proteins
- Abstract
Cells derived from an epithelial-mesenchymal transformation within the atrioventricular canal and outflow tract are involved in the partitioning of the early embryonic heart into a four-chambered organ. This transformation process has been shown to proceed from an inductive interaction between the myocardium and competent, target endothelial cells within these regions of the heart. Interestingly, immunohistochemistry revealed the presence of fibronectin-positive particulates within the matrix of mesenchyme-forming regions (Mjaatvedt et al., 1987). This particulate matrix is extractable by EDTA and can elicit the epithelial-mesenchymal transformation in culture (Mjaatvedt and Markwald, 1989). Analysis of EDTA extracts of embryonic heart tissue revealed the presence of fibronectin and about 40 unidentified proteins, 6 of which appeared to be enriched in the biologically active 100,000g pellet fraction (Mjaatvedt and Markwald, 1989). Based on these and other data we have proposed that the particulate matrix is composed of a multicomponent complex of fibronectin and one or more of the low-molecular-weight proteins in this pellet. The purpose of the present study was to begin a biochemical characterization of the nonfibronectin proteins thought to be present in the matrix particulates. Given that many matrix constituents are glycoproteins, lectins were used to initially characterize the particulate constituents. Of the lectins tested, soybean agglutinin (SBA) was found to be specific only for matrix particulates. Histochemical analyses showed that SBA and antibodies against fibronectin colocalized regionally and temporally to the same matrix particulates in embryonic heart tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1992
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7. Morphogenesis of precursor subpopulations of chicken limb mesenchyme in three dimensional collagen gel culture.
- Author
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Markwald RR, Bolender DL, Krug EL, and Lepera R
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- Animals, Culture Techniques, Microscopy, Electron, Chick Embryo growth & development, Extremities embryology
- Abstract
Although homogeneous in appearance, several lines of evidence suggest early (stage 17-19) limb mesenchymal cells are committed to particular cell lineages, e.g., myogenic or chondrogenic. However, subsequent expression of cell or tissue phenotype in the developing limb does not occur in a randomized process but rather in a spatially specific pattern. The potential regulatory mechanisms controlling the "patterned" expression of tissue phenotype in the limb have not been resolved. The purpose of this study was to determine if, prior to the formation of an apical ectodermal ridge, nondissociated limb mesenchyme has inherent morphogenetic potential to form nonrandomized patterns of tissue organization. The hypotheses to be tested were that, if provided a spatially permissive culture environment, 1) mesenchymal cells committed to a particular lineage would segregate into precursor (sub)populations prior to overt expression of phenotype and 2) the ultimate expression of a tissue phenotype may be regulated, in part, by histogenic interactions between the precursor cell groups. For these studies, mesoblasts (intact mesenchyme minus ectoderm) from stage 17-19 hindlimb buds were explanted intact to the surface of a 1-3 mm thick hydrated lattice of repolymerized type I collagen and incubated for 2-11 days. Examination of cultures at variable intervals revealed three distinct temporal sequences (periods) which were arbitrarily termed early morphogenesis (0-3 days), cytodifferentiation (3-5.5 days), and primitive tissue formation (5.5-11 days) based on similarities to in situ limb development. By the end of the first period, the mesenchymal cells had sorted into three distinct precursor populations: 1) an epithelial-like outgrowth of premyogenic and prefibrogenic cells at the surface of the gel lattice (termed the "surface subset") which circumscribed, 2) a centrally positioned prechondrogenic condensate ("central subset"), and overlaid 3) a dispersed, population of free cells that invaded the collagen lattice ("seeded subset"). Subsequent cytodifferentiation led to the appearance of multinucleated myotubes within the surface subset and chondrification of the central subset. Cells of the seeded subset remained dispersed within the collagen lattice. Primitive histogenic events were initiated during the final period of development including 1) at sites where surface cells established boundaries with the central subset, collectives or "bundles" of variable sized myotubes were formed which became partially ensheathed by the attenuated processes of fibroblastlike cells; and 2) a secondary site of chondrogenic activity was initiated within the gel lattice at the boundary between the central and seeded cell populations. Transformation of seeded fibroblasts into chondroblasts accompanied expansion of the secondary chondrogenic element within the gel lattice.(ABSTRACT TRUNCATED AT 400 WORDS)
- Published
- 1990
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8. Histological analysis of limb regeneration in postmetamorphic adult Ambystoma.
- Author
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Young HE, Bailey CF, Markwald RR, and Dalley BK
- Subjects
- Alcian Blue, Ambystoma anatomy & histology, Animals, Forearm physiology, Hematoxylin, Periodic Acid-Schiff Reaction, Wound Healing, Ambystoma physiology, Extremities physiology, Regeneration
- Abstract
Previous investigation into the regenerative ability of postmetamorphic adult land phase Ambystoma has revealed that these species have the capacity to completely regenerate a limb, given optimal environmental conditions, and the gross morphological characteristics of limb regeneration in these species compared favorably with the external regeneration morphology of aquatic phase forms. The present study concerns a histological and histochemical examination of the regenerating limb tissues and their respective extracellular and intracellular tissue matrices. Postmetamorphic adult Ambystoma were amputated through the forearm, placed within optimal environmental conditions, and allowed to regenerate. The tissues were harvested at designated intervals after amputation and prepared for light microscopic examination. The limb tissues were assayed histologically for similarities to and differences from previously established regeneration morphologies. It was noted that specific correlations (i.e., apical epidermal cap formation, but outgrowth and elongation, palette formation, and digit formation) existed between regeneration histologies in these species and those previously reported for the aquatic urodeles, newt, axolotl, and larval salamander. By utilizing the histological and histochemical characteristics of the tissue, the regenerate limb was divided into five tissue units: epidermal, blastemal, soft, hard, and neuro/vascular. Based on the unique morphology of their extracellular matrices and respective histochemical staining patterns, four distinct blastemal regions were delineated within the blastemal units: subregenerate epidermal blastema, soft-tissue blastema, hard-tissue blastema, and core blastema. Histochemically, changing patterns of highly sulfated, weakly sulfated, and carboxylated polysaccharides and glycosylated compounds were located within both the extra- and intracellular stump and regenerate tissue matrices during regeneration. In addition, these patterns of intra- and extracellular macromolecular material correlated to previous reports of similar-type compounds assayed during regeneration in aquatic urodeles. With this in mind, the adult land phase Ambystoma can be considered an appropriate model system for studies concerning normal limb regeneration.
- Published
- 1985
- Full Text
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9. Glycoconjugates in normal wound tissue matrices during the initiation phase of limb regeneration in adult Ambystoma.
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Young HE, Dalley BK, and Markwald RR
- Subjects
- Animals, Chondroitin Sulfates analysis, Dermatan Sulfate analysis, Epidermal Cells, Epidermis physiology, Extremities analysis, Extremities injuries, Glycoproteins analysis, Hyaluronic Acid analysis, Keratan Sulfate analysis, Microchemistry, Phenotype, Spectrophotometry methods, Ambystoma physiology, Extremities physiology, Glycoconjugates analysis, Regeneration
- Abstract
The present study identifies, localizes, and reports the relative composition of specific glycosaminoglycans within tissue matrices during the initiation phase of limb regeneration. The regenerate tissues were harvested and assayed morphologically, histochemically, and chemically. We observed 1) a population of cells interspersed among the cells of the dermis, epimysium, perimysium, perichondrium, and periosteum. 2) This population was distinguishable by a unique pattern of glycoconjugate staining, i.e., intracellular and pericellular heparan sulfate and glycoproteins and extracellularly associated hyaluronate and glycoproteins. 3) Cells with these staining characteristics aggregated to a position directly beneath the apical epidermal cap. 4) Extracellular hyaluronate and glycoproteins colocalized with undifferentiated tissues. And 5) extracellular chondroitin sulfate, dermatan sulfate, and keratan sulfate glycosaminoglycans colocalized with differentiated tissues. The correlations of distinct glycoconjugate compositions with specific regeneration morphologies suggest the possibility that these components may be related to the phenotypic expression of tissues during regeneration.
- Published
- 1989
- Full Text
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10. Distribution of basement membrane antigens in cryopreserved early embryonic hearts.
- Author
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Kitten GT, Markwald RR, and Bolender DL
- Subjects
- Animals, Chick Embryo, Collagen analysis, Collagen immunology, Extracellular Matrix analysis, Fibronectins analysis, Fibronectins immunology, Freezing, Laminin analysis, Laminin immunology, Myocardium immunology, Myocardium ultrastructure, Preservation, Biological, Basement Membrane analysis, Heart embryology, Myocardium analysis
- Abstract
The early embryonic heart is composed of two cylindrical epithelial layers, an inner endothelium and an outer myocardium. The cardiac jelly (CJ), an acellular accumulation of extracellular matrix (ECM), fills the space between the two epithelia. During development of the heart, a portion of the endothelial cells of the atrioventricular (AV) region differentiate into mesenchyme cells in a temporally and spacially specific manner. Although contiguous with those in the AV region, endothelial cells lining the ventricle never form mesenchyme in situ. At present, the mechanisms controlling the biphasic differentiation of the endothelium and the subsequent migration of cardiac mesenchymal cells are poorly understood. Although the CJ lies between two epithelial and is spatially equivalent to a basement membrane (BM), it has not traditionally been considered to be organized into a BM-like structure. The potential significance of this observation to developmental biology lies in the possibility that BM or their individual components (i.e., fibronectin (FN), laminin (LM), type IV collagen, and heparin sulfate proteoglycan (HSPG] may function as the regulatory site of epithelial differentiation and morphogenesis. A cryofixation technique was developed in order to determine the in situ immunohistochemical distribution of the BM components in the CJ. Results indicated that the CJ exists as the fusion between a larger myocardially derived BM having a lamina densa and an extended reticular lamina and an attenuated, endothelial-associated BM composed only of a lamina densa. Except for FN, the individual BM components were not all present during early stages, but instead appeared in a sequential manner, suggesting that all components of an adult-type BM are not required to initiate the assembly of a structural and functional BM during development. In the AV canal and outflow tract (OT), FN appeared as a progressively expanding gradient of material with the greatest density nearer the myocardium.
- Published
- 1987
- Full Text
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11. Effect of selected denervations on glycoconjugate composition and tissue morphology during the initiation phase of limb regeneration in adult Ambystoma.
- Author
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Young HE, Dalley BK, and Markwald RR
- Subjects
- Animals, Chondroitin Sulfates analysis, Denervation, Extremities analysis, Extremities cytology, Glycoproteins analysis, Heparitin Sulfate analysis, Hyaluronic Acid analysis, Ambystoma physiology, Extremities physiology, Glycoconjugates analysis, Regeneration
- Abstract
This study was undertaken to assess the effects of various quantities of neural tissue on the temporal relationship of matrix glycoconjugates to the regeneration morphology. 1) Denervation before amputation revealed that a threshold level of nervous tissue was necessary to activate a regeneration response from the tissue, i.e., appearance of regeneration-specific morphologies and glycoconjugates. 2) Denervation after amputation demonstrated that the level of neural tissue necessary to maintain these responses was below the level necessary to activate the regeneration response. If neural tissue was completely removed there was a concomitant loss of regenerate morphologies and glycoconjugates. 3) Bilateral amputation of a neurogenically intact limb and its completely denervated contralateral limb revealed that the regeneration response was a localized phenomenon during the first 30 days after amputation. After 30 days the regeneration response appeared within the previously degenerated denervating limb. The results suggest that the factors controlling the regenerative response in adult Ambystoma are large diffusible substances that can be transported by the circulation and can affect the regenerative response in remote, previously activated, tissues.
- Published
- 1989
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12. Specific configurations of fibronectin-containing particles correlate with pathways taken by neural crest cells at two axial levels.
- Author
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Brauer PR and Markwald RR
- Subjects
- Animals, Cell Movement, Chick Embryo, Lectins metabolism, Neural Crest physiology, Staining and Labeling, Sulfates metabolism, Tissue Distribution, Ectoderm metabolism, Extracellular Matrix metabolism, Fibronectins metabolism, Neural Crest cytology
- Abstract
Although neural crest (NC) cells can potentially enter a number of intertissue spaces, they select a particular pathway that varies depending on the axial level. In the cranial region, NC cells enter the dorsal-lateral pathway (i.e., immediately subjacent to the ectoderm) and avoid the ventral pathway (i.e., pathway between the mesoderm and neural tube and within the mesodermal cell population), whereas in the trunk region, the majority of the NC cells enter the ventral pathway (i.e., between the somite and neural tube) and not the dorsal-lateral pathway. Our working hypothesis is that one determining factor in directing NC cell migration is the composition and/or intermolecular associations of the extracellular matrix (ECM) in these pathways. Histochemical staining, immunostaining, and lectin-binding studies on cryofixed and conventionally fixed tissue were conducted to initially characterize the ECM found in potential NC cell pathways prior to and during initial NC cell migration at two different axial levels. We found that, regardless of the axial level, the pathways into which NC cells eventually enter possessed a characteristic ECM arrangement. This arrangement included: 1) the presence of multicomponent, glycoprotein-containing spherical particles (0.1-0.5 micron in diameter); and 2) a low-sulfated ECM content. Although all particles contained fibronectin, only those in specific regions were able to bind to a monoclonal antibody directed to the cell-binding domain of fibronectin, suggesting that the conformation of fibronectin may be important in the expression of any in situ function of the molecule.
- Published
- 1988
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13. Effects of two glycosaminoglycans on seeding of cardiac cushion tissue cells into a collagen-lattice culture system.
- Author
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Bernanke DH and Markwald RR
- Subjects
- Animals, Cells, Cultured, Chick Embryo, Endothelium embryology, Chondroitin analogs & derivatives, Chondroitin Sulfates pharmacology, Collagen physiology, Heart embryology, Hyaluronic Acid pharmacology
- Abstract
A collagen-lattice culture model of developing heart valves was utilized to test two glycosaminoglycans, normally found in the cardiac jelly matrix of developing heart valve primordia, for their effects on the capability of mesenchymal derivatives of cardiac cushion endothelial cells to enter the substrate from the surface. Treatment with hyaluronate increased the rate of cell seeding to 2.04 times that of untreated control cultures and 1.82 times that of chondroitin sulfate-treated cultures. Scanning electron microscopic studies suggested that the increased rate was due to an enhanced disruption of intercellular junctions, influenced by hyaluronate, permitting disengagement of cells from the surface population and migration as mesenchymal cells into the collagen matrix. The results of this study correlate well with the presence of high hyaluronate concentrations in the cardiac jelly matrix beneath the cushion endothelium at periods of active seeding of cushion tissue cells.
- Published
- 1984
- Full Text
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14. Attachment of neural crest cells to endogenous extracellular matrices.
- Author
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Brauer PR and Markwald RR
- Subjects
- Adsorption, Animals, Cell Adhesion, Cell Movement, Chick Embryo, Ectoderm ultrastructure, Kinetics, Microscopy, Electron, Plastics, Temperature, Extracellular Matrix physiology, Neural Crest cytology
- Abstract
Newly emerging neural crest (NC) cells will enter either the lateral pathway under the surface ectoderm or the vental pathway along the neural tube depending on the axial level (Pratt et al.: Dev. Biol., 44:298-305, 1975; Thiery et al.: Dev. Biol., 93:324-343, 1982; Newgreen et al.: Cell Tissue Res., 221:521-549, 1982; LeDouarin et al.: In: The Role of Extracellular Matrix in Development. Alan R. Liss, Inc., New York, pp. 373-398, 1984; Brauer et al.: Anat. Rec., 211:57-68, 1985). A number of studies have shown a correlation between the type of extracellular matrix (ECM) associated with adjacent tissues (e.g., ectoderm, neural tube, and mesoderm) and the initial pathway taken by NC cells. Our working hypothesis is that the direction of NC cell migration (ventral vs. lateral pathway) depends on the composition of the ECM associated with the surface ectoderm and its ability to support NC cell attachment. In this study, we tested this hypothesis by isolating endogenous ECM associated with the ectoderm of each region and examining the ability of each endogenous ECM to support cranial and trunk NC cell attachment in vitro. Results indicated that both cranial and trunk NC cells preferentially attached to cranial ectodermal ECM as compared to trunk ectodermal ECM. The differences in NC cell attachment were not due to a preferential adsorption of cranial ectodermal ECM onto the ECM-conditioned plastic substrate over trunk ectodermal since approximately equal amounts of ECM bound to the plastic. These results supported the hypothesis and provide evidence that endogenous ectodermal ECM may be one factor potentially responsible for directing the NC cells along a ventral or a lateral pathway.
- Published
- 1987
- Full Text
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15. A histochemical analysis of polyanoinic compounds found in the extracellular matrix encountered by migrating cephalic neural crest cells.
- Author
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Bolender DL, Seliger WG, and Markwald RR
- Subjects
- Alcian Blue, Animals, Anions analysis, Cell Movement, Chick Embryo, Colloids, Histocytochemistry, Hydrogen-Ion Concentration, Iron, Morphogenesis, Neural Crest analysis, Neural Crest ultrastructure, Staining and Labeling, Glycosaminoglycans analysis, Neural Crest cytology
- Abstract
Neural crest cells destined to form craniofacial primordia initially are "seeded" into and subsequently migrate through the extracellular matrix (ECM) of a cell free space (CFS) between the surface ectoderm and the underlying mesoderm. Utilizing histochemical procedures for polyanionic compounds, we have demonstrated that both sulfated and nonsulfated glycosaminoglycans (GAG) are present in the CFS of the cephalic region of the chick embryo and that their distribution and structural organization vary with the passage of neural crest or mesodermally derived (MD) mesenchymal cells through it. In stages 7 and 8 embryos a predominance of fine filamentous strands composed primarily on nonsulfated, carboxyl-rich GAG is seen spanning intercellular spaces between adjacent tissues and MD mesenchymal cells. In older embryos (stages 9 and 10) much of the filamentous material is replaced by coarse fibrillar strands or amorphous material which coats the surfaces of MD mesenchymal and neural crest cells as they invade the CFS. Using enzymatic digestions (Streptomyces and testicular hyaluronidase) and the critical electrolyte concentration procedure, data suggest that the fine filamentous matrix onto which the neural crest cells migrate consists mainly of hyaluronate with lesser amounts of chondroitin and some sulfated GAG present. The coarse fibrillar matrix that appears after passage of either neural crest or MD mesenchymal cells through the original CFS contains strongly sulfated polyanionic material, predominantly chondroitin sulfates A, C. Since GAG is located ubiquitously within the ECM of embryos at various stages, the role of GAG, if any, in the transfer of developmental information may be of a general nature (ie. stimulus of motility) rather than of specific morphogenetic cues (for specific differentiation into craniofacial primordia).
- Published
- 1980
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16. The distribution and spatial organization of the extracellular matrix encountered by mesencephalic neural crest cells.
- Author
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Brauer PR, Bolender DL, and Markwald RR
- Subjects
- Animals, Autoradiography, Cell Movement, Chick Embryo, Extracellular Matrix physiology, Histocytochemistry, Neural Crest physiology, Extracellular Matrix ultrastructure, Mesencephalon embryology, Neural Crest cytology
- Abstract
Cephalic neural crest (NC) cells enter a cell-free space (CFS) that contains an abundant extracellular matrix (ECM). Numerous in vitro investigations have shown that extracellular matrices can influence cellular activities including NC cell migration. However, little is known about the actual ECM composition of the CFS in vivo, how the components are distributed, or the nature of NC cell interactions with the CFS matrix. Using ultrastructural, autoradiographic, and histochemical techniques we analyzed the composition and spatial organization of the ECM found in the CFS and its interaction with mesencephalic NC cells. We have found that a specific distribution of glycoproteins and sulfated polyanions existed within the CFS prior to the translocation of NC cells and that this ECM was modified in areas occupied by NC. The interaction between the ECM components and the NC cells was not the same for all NC cells in the population. Subpopulations of the NC cell sheet became associated with ECM of the ectoderm (basal lamina) while other NC cells became associated with the ECM of the CFS. Trailing NC cells (NC cells that emerge after the initial appearance of NC cells) encountered a modified ECM due to extensive matrix modifications by the passage of the initial NC cell population.
- Published
- 1985
- Full Text
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17. Endocytic activity in embryonic cardiac cushion mesenchyme in vivo and in collagen gel lattices.
- Author
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Hay DA, Markwald RR, and Sage AP
- Subjects
- Animals, Cations, Cells, Cultured, Chick Embryo, Ferritins metabolism, Horseradish Peroxidase metabolism, Muramidase metabolism, Myocardium metabolism, Collagen, Endocytosis, Heart embryology
- Abstract
Mesenchymal cells, termed cushion tissue (CT) cells, are the principal cellular elements in atrioventricular (AV) endocardial cushions, the latter constituting AV septal and valvular primordia in the embryonic heart. Atrioventricular canals of 2 1/2 day chick embryo hearts were explanted onto collagen gel lattices, wherein cushion endothelial cells acquired the characteristics of CT cells and invaded the gel. The endocytic activity of in situ CT cells was compared to that of gel-cultured CT cells by exposing appropriate preparations to horseradish peroxidase (HRP), cationized ferritin (CF) or to lysozyme. Stimulation by these exogenous proteins resulted in phagocytosis. In addition, all three markers were associated with coated pits, smooth surfaced vesicles (45-60 nm), C- or cup-shaped structures and other lysosomal elements, but were excluded from Golgi cisternae and their entire vesicle population. In CT cells, HRP does not act solely as a "content" marker that reflects fluid-phase uptake. Instead it appears to follow adsorptive endocytic pathways. The endocytic behavior of in vivo and in vitro cushion tissue cells appears to be the same. Endogenous endocytic activity may reflect in part membrane retrieval, which counterbalances the extensive exocytosis observed in these cells.
- Published
- 1983
- Full Text
- View/download PDF
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