ISSN:
0362-2525
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
An ultrastructural analysis of the development of adult piston (tongue) cartilage in the ventromedial longitudinal bar (VMLB), an area of larval mucocartilage, was undertaken in the lamprey, Petromyzon marinus, in order to clarify the relationship between these two unique larval and adult connective tissues. At the onset of metamorphosis, the mucocartilage fibroblasts dedifferentiate into a “mesenchymal” cell type. Migration of unspecialized cells from surrounding tissues plays an important role in the development of a cellular “embryonic” tissue in the VMLB. Degradation of the mucocartilage extracellular matrix (ECM) by the unspecialized cells seems to occur prior to cartilage differentiation. This event is followed by the appearance of a blastema of undifferentiated cells, which expands by proliferation of cells in the core of the VMLB. The cells of the blastema subsequently differentiate into chondroblasts, which secrete adult ECM components consisting of 20-nm nonbanded fibrils, electron-dense branched lamprin fibrils, and proteoglycan. The present study suggests that mucocartilage, as a primitive or embryonic connective tissue, temporarily specializes to act as a skeletal support during larval life. Once metamorphosis is initiated, this tissue resumes an embryonic character (mesenchymal) and cartilage histogenesis takes place. The mechanism of cartilage development within the lamprey VMLB is similar to that observed in the chondrogenic system of higher vertebrates.
Additional Material:
24 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmor.1051940102
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