ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
During embryonic tooth formation, interactions between epithelial and mesenchymal cells results in the formation of a metachromatic interface or extracellular matrix. The cervical or germinative region of this epidermal organ system is populated by an increasing gradient of cellular differentiation and an extracellular matrix which is the progenitor for subsequent dentine organic matrix formation. Embryonic rabbit tooth primordia can be maintained in culture enabling kinetic studies of labeled precursor incorporation. Autoradiographs of tooth organ cultures continusly incubated with labeled uridine for periods up to eight hours, demonstrated initial cellular incorporation with subsequent transfer of 2% of the grain density to the extracellular matrix by four hours. The grain density was removed by ribonuclease treatment. No incorporation of tritiated thymidine into the matrix was observed. The incorporation of C14-uridine during organ culture was inhibited by actinomycin D. Micrurgy was employed to isolate the extracellular matrix free of adherent cells. Electron microscopy demonstrated membrane-bound, electron dense bodies within the matrix, presumably cytoplasmic extensions. No cells per se were observed on the isolated matrix. Several experimental criteria suggested that uridine incorporation into the extracellular matrix was regulated by epithelial and mesenchymal cells. Phenol extraction procedures of labeled cervical matrices demonstrated an ultraviolet absorption maximum at 260 μU. Both spectrophotometric determinations and orcinol assays found RNA to be 0.4-0.5% of the cervical extracellular matrix.These results are interpreted to indicate that RNA is a component of the metachromatic extracellular matrix during epithelio-mensenchymal interactions associated with tooth formation. The functional significance of these observations is premature at this time.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1040730304
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