Development of the axial cartilaginous skeleton in the regenerating tail of lizards.

In order to study the pattern of growth of regenerating cartilage, H3-thymidine was injected in individuals of the lizards Anolis carolinensis and Lampropholis delicata during advanced stages of tail regeneration. Light and electron microscopic autoradiographical analysis showed that the regenerating cartilaginous tube was mostly derived from the interstitial proliferation of chondroblasts. Appositional growth is limited during the initial stages of cartilage formation. Later, after the differentiation of an inner and outer perichondrium, a few cells were added to the cartilaginous tube while cellular degeneration of the calcifying areas was in progress. In this way a constant diameter of the cartilaginous tube was maintained. In order to study the rate of production of matrix protein (collagen), H3-proline was administered to other samples of Lampropholis. To the best of the author's knowledge this was done for the first time in the cartilage of a reptiles. The tracier was mostly localized in the apical-intermediate cartilage and one hour postinjection it was mostly concentrated in the ergastoplasm around the Golgi apparatus and its secretory vesicles. Three hours after the injection of H3-proline some of the tracier was found in the cytoplasm of chondrocytes and in the extracellular matrix.