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H C Slavkin

Publications and source records attributed to H C Slavkin.

At least 235 records · Page 13Linked to original sources
PubMed1981

Possible functions of mesenchyme cell-derived fibronectin during formation of basal lamina.

Epithelial synthesis and secretion of basal lamina has been considered to be a general feature of various vertebrate epithelium-mesenchyme interacting systems (e.g., salivary gland, mammary gland, feather, hair, and tooth morphogenesis). It has been repeatedly assumed that embryonic ectoderm and ectodermal derivatives, such as epithelial tissues associated with tooth morphogenesis, synthesize and secrete basal lamina. Basal lamina of embryonic mouse tooth organs contain laminin, type IV collagen, glycosaminoglycans, and possibly fibronectin. Ectodermally derived epithelia produce laminin, collagens, and glycosaminoglycans but they do not appear to produce fibronectin. Mesenchyme can effect basal lamina formation in vitro by releasing mesenchyme-derived fibronectin. Theiler stage 25 molar tooth mesenchymal and epithelial tissues were enzymatically separated and cultured in chemically defined media without serum, embryonic extracts, or antibiotics for periods not exceeding 24 hr. Isolated epithelia did not reconstitute a basal lamina. Mesenchymepreconditioned media, fibronectin substrata, or addition of 10% fetal calf serum induced reconstitution of epithelium-derived basal lamina. Dental mesenchyme-preconditioned medium contained, as a major component, a protein of M(r) approximately 2.3 x 10(5) identified as fibronectin by the criteria of gelatin binding and subunit molecular weight. Fibronectin was not produced by isolated epithelia. These results support the hypothesis that basal lamina ultrastructural organization results from supramolecular interactions between epithelium-derived macromolecules (e.g., type IV collagen, proteoglycans, glycosaminoglycans, and laminin) with mesenchyme-derived cell surface fibronectin.

Animals↗
PubMed1981

Epithelial-directed mesenchyme differentiation in vitro model of murine odontoblast differentiation mediated by quail epithelia.

To assess the requirement for specific or possibly non-specific epithelial instructions for mesenchymal cell differentiation, we designed studies to evaluate and compare homotypic with heterotypic tissue recombinations across vertebrate species. These studies further tested the hypothesis that determined dental papilla mesenchyme requires epithelial-derived instructions to differentiate into functional odontoblast cells using a serumless, chemically-defined medium. Theiler stage 25 C57BL/6 or Swiss Webster cap stage mandibular first molar tooth organs or trypsin-dissociated, homotypic epithelial-mesenchymal tissue recombinants resulted in the differentiation of odontoblasts within 3 days. Epithelial differentiation into functional ameloblasts was observed within 7 days. Trypsin-dissociated and isolated mesenchyme did not differentiate into odontoblasts under these experimental conditions. Heterotypic recombinants between quail Hamburger-Hamilton stages 22-26 mandibular epithelium and Theiler stage 25 dental papilla mesenchyme routinely resulted in odontoblast differentiation within 3 days in vitro. Odontoblast differentiation and the production of dentine extracellular matrix continued throughout the 10 days in organ culture. Ultrastructural observations of the interface between quail and mouse tissues indicated the reconstitution of the basal lamina as well as the maintenance of an intact basal lamina during 10 days in vitro. Quail epithelial cells did not differentiate into ameloblasts and no enamel extracellular matrix was observed. These results show that quail mandibular epithelium can provide the required developmental instructions for odontoblast differentiation in the absence of serum or other exogenous humoral factors in a chemically-defined medium. They also suggest the importance of reciprocal epithelial-mesenchymal interactions during epidermal organogenesis.

Ameloblasts↗
PubMed1981

Influence of nerve growth factor on the embryonic mouse trigeminal ganglion in culture.

Developing trigeminal ganglia have been excised from mouse embryos of 9, 10, 11 and 12 days gestation and grown in tissue culture. A quantitative method was used to assess the effect of nerve growth factor (NGF) and an antiserum to NGF (anti-NGF) on fiber outgrowth from the explanted ganglia. Fiber outgrowth from 9-day ganglia (E9 ganglia) appeared to be unaffected by the presence of NGF. However, the ganglia became increasingly responsive to NGF from embryonic day 10 through 12. The increased responsiveness to NGF in vitro coincided with the establishment of fiber contacts with peripheral target tissues in vivo. Anti-NGF produced no significant reduction of fiber outgrowth from E9 ganglia, but from later ganglia significant reduction were observed.

Animals↗
PubMed1981

Neurite outgrowth from murine sensory ganglia cultured in a serumless medium.

Trigeminal and dorsal root ganglia were excised from mouse embryos of 10 and 18 days in utero age, respectively, and grown in tissue culture. A quantitative method was used to assess the extent of neurite outgrowth from the explants after 24 and 48 h in culture. Outgrowth from ganglia grown in a serumless medium was compared with that from ganglia in a medium supplemented with serum. There was no significant difference between the extent of outgrowth in either medium after 24 h in culture; however, after 48 h there was significantly greater outgrowth in the serum-supplemented medium.

Animals↗
PubMed1981

Spatiotemporal patterns of fibronectin distribution during embryonic development. I. Chick limbs.

It has been suggested that an extracellular matrix - and cell surface - associated glycoprotein, fibronectin, plays a role in the positioning of cells in morphogenesis and in the maintenance of orderly tissue organization. In the present study the appearance and distribution of fibronectin during in ovo chick limb development has been investigated by indirect immunofluorescence techniques in H.H. stages 20-30. Fibronectin is not detectable until just prior to the transition from the morphogenetic to the cytodifferentiation phase of development. Beginning at H.H. stage 25, successive nonrandom patterns of fibronectin detection and distribution, which resemble the subsequent cartilaginous elements, precede overt chondrogenesis as detected by Alcian blue staining. This corresponds to the onset of the cytodifferentiation phase of limb development. As the accumulation of acidic proteoglycan increases in the cartilage matrix and the mesenchymal cells become more round in appearance, the presence of detectable fibronectin decreases and is ultimately seen only in the perichondria and basement membrane. However, predigestion of developed cartilage tissue with testicular hyaluronidase, prior to fibronectin staining, indicated that fibronectin remains a major constituent of cartilage matrix and is apparently masked by cartilage-specific proteoglycans. This study of chick limb development is consistent with the hypothesis that fibronectin may be a molecule that facilitates the spatial organization of cartilaginous primordia cytodifferentiation.

Animals↗
PubMed1981

Spatiotemporal patterns of fibronectin distribution during embryonic development. II. Chick branchial arches.

It has recently been demonstrated with the chick limb in ovo that successive nonrandom patterns of fluorescent staining with specific antibodies to fibronectin indicate the cartilagenous primordia prior to overt chondrogenesis. Given the apparent nonequivalence of embryonic cartilages, the purpose of this study was to determine whether this phenomenon was unique to developing chick limbs or is a more general characteristic of chondrogenesis. The appearance and distribution of fibronectin during chick first and second branchial arch development in ovo was investigated by indirect immunofluorescence techniques in H.H. stages 15-26. Fibronectin can be detected in early stages in areas presumed to be composed mainly of ectomesenchyme. During later stages of development, successive nonrandom patterns of fibronectin distribution appear to precede overt chondrogenesis as demonstrated by alcian blue staining. Pretreatment of cartilage with testicular hyaluronidase, prior to fibronectin staining, revealed that fibronectin was still present, suggesting that it was masked by proteoglycans. Fibronectin was also detected in the developing membrane bones of the mandible. The nonrandom patterning of fibronectin distribution in ovo in chick branchial arches and limb buds, respectively derived from neural crest and somatic mesoderm, were similar. It appears that specific patterns of fibronectin distribution were characteristic of chondrogenesis, regardless of the embryonic origin of the cartilage. This phenomenon may prove to be an extremely useful probe for early developmental skeletal abnormalities.

Animals↗
PubMed1980

Isolation and preliminary characterization of epithelial-specific messenger ribonucleic acids and their products during embryonic tooth development.

Experiments were designed to identify and characterize tissue-specific proteins involved in the process of tooth organogenesis. Epithelial and mesenchymal proteins were extracted from intact molar organs or mechanically separated tissues obtained from 25-day New Zealand White rabbit embryos. Labelling experiments with [35S]methionine followed by radioautography or gel electrophoresis and fluorography showed the presence of label only in epithelial proteins. Most of these proteins range from 43 000 mol.wt. and higher, except for one band of approx. 16 000 mol.wt. A mRNA fraction of 16--26S was isolated by ultracentrifugation on sucrose gradients. When translated in a reticulocyte-lysate cell-free system, the mRNA obtained from intact molar organs resulted in the synthesis of three proteins, of mol.wts. 65 000, 58 000 and 43 000. A similar mRNA fraction obtained from dental-pulp mesenchyme gave only the 43 000-mol.wt. protein, indicating that the 65 000- and 58 000-mol.wt. proteins are derived from epithelial cells.

Ameloblasts↗
PubMed1980

Role of basal lamina in tissue interactions.

Basal lamina are extracellular structures found closely apposed to the plasma membrane on the basal surface of epithelial and endothelial cells and surround muscle and fat tissues. While the primary function of basal lamina in most adult tissues is probably supportive, significant evidence indicates that during embryonic development, basal lamina may be involved in regulating heterotypic tissue interactions. Changes in composition of the basal lamina of salivary and mammary gland epithelial tissues during development probably are important for branching morphogenesis which leads to the final form of the organ. During tooth organogenesis, selective basal lamina degradation and direct cell contact between developing epithelium and mesenchyme has been documented and suggested to be necessary for cytodifferentiation. Basal lamina turnover, as suggested by these morphological observations, no doubt involves both basal lamina synthesis and degradation. We have studied several factors evidently required for basal lamina reconstitution in vitro, and have discovered that fibronectin added to enamel organ epithelial cultures provided cues required for basal lamina formation in vitro. Both fetal calf serum and dental papilla mesenchyme-conditioned media also provided specific signals for basal lamina reconstitution. In addition, we have found that fibronectin is produced by the dental papilla mesenchyme, is released into the medium, and can be isolated from epithelial explants which have been cultured in mesenchyme-conditioned medium; the epithelial explants themselves do not make fibronectin in vitro.

Amelogenesis↗
PubMed1980

Chemically-defined organ culture of embryonic mouse tooth organs: morphogenesis, dentinogenesis and amelogenesis.

Chemically-defined in vitro conditions without serum have been identified which are permissive for embryonic mouse tooth organs to express morphogenesis and cytodifferentiation. In the absence of antibiotics, embryonic extracts, autologous and/or heterologous sera, molar tooth organs from Theiler stage 25 embryos (C57BL/6, A/Jax and Tabby mouse strains) routinely formed discrete dentin and enamel extracellular organic matrices within 10 days of continuous in vitro cultivation. Collagen and non-collagenous protein synthesis and secretion by differentiated cells within explants, between 9 and 10 days in vitro, were studied with light microscopic autoradiography. Finally, explants of embryonic mouse molar tooth organs have been maintained in organ culture for three week without serum supplementation.

Amelogenesis↗
PubMed1979

An antisera for the fluorescent labeling of mouse amelogenesis.

Embryonic mammalian enamel extracellular matrix is immunogenic. Antisera has been produced in New Zealand white rabbits using 5-day-old (post-natal) C57B1/6J mandibular and maxillary incisor and molar tooth organs as immunogens. The expression of secretory amelogenesis in mouse molar tooth organs was studied from the "cap stage" (circa 17-day fetus) to the fifth day of postnatal odontogenesis using indirect immunofluorescent microscopy. The specificity of the antisera for enamel matrix secretion was unequivocal. Secretory amelogenesis was observed in molar tooth organs as early as day-2 postnatal age. These reagents and methods provide a significant strategy in studies of epithelial-mesenchymal interactions during tooth development.

Amelogenesis↗
PubMed1979

Amelogenesis in vitro.

The processess by which diversity is acquired and maintained during embryogenesis have been repeatedly described but are as yet not understood. One fascinating example of diversity following gastrulation is epidermal organogenesis and in particular embryonic tooth morphogenesis. Tooth morphogenesis in situ and in vitro encompasses such interesting developmental problems as epithelial-mesenchymal interactions, cytodifferentiation, dentine and enamel extracellular matrix production, mineralization, issues of form and enamel maturation. In vitro methods provide access to many of these problem areas. This presentation will review selected issues related to amelogenesis in vitro and will emphasize avenues for future research.

Ameloblasts↗
PubMed1979

Speculations regarding the influence of the major histocompatibility complex (H-2) upon congenital craniofacial malformations in inbred and congenic strains of mice.

Investigations in different mammalian species have demonstrated a remarkable degree of analogy between distant mammalian species. All mammals possess a major histocompatilibity complex. The identified and postulated functions for the MHC appear to be similar among all mammalian species [14, 25]. One fascinating, but still unconfirmed possibility is that the MHC functions to regulate the immunobiology of normal pregnancy. It should be stressed at this point that much more knowledge is necessary to elucidate the mechanism of H-2-disease associations in mice and HLA-disease associations in man [25]. One explanation of the observed H-2 and HLA-disease associations is linkage disequilibrium. Data are available suggesting a tenuous HLA--cleft lip and/or palate association [34, 35] but the data are equivocal. The available data from congenic mice studies are considerably less equivocal and strongly suggest several important future approaches. Identification of the H-2a haplotype susceptibility and the H-2b resistance to steroid-induced clefting is a major advance in this complex field [36]. Available methods are sensitive, and newer, more precise methods are now in the offing. The renaissance in the field of congenital craniofacial malformations is rather exciting, especially the renewed awareness of interdisciplinary research toward ultimate prevention. Understandably, many physicians, dentists, nurses, and pharmacists, as well as allied biomedical health professionals investigating the heredity of congenital craniofacial malformations, are deeply interested in immunogenetics. In tandem, the biomedical scientific community (eg developmental biologists, molecular biologists, immunologists) wish to learn more about the complicated and often overlapping relationships between various clinical features of the diseases concerned. All are aware that our knowledge of this fascinating subject will not stand still; many are busy changing it.

Animals↗