Morphometric study of cartilage dynamics in the chick embryo tibia. II. Dexamethasone-treated embryos.

The cartilage dynamics in the tibia of dexamethasone-treated chick embryos has been studied by means of morphometric methods. Treated embryos showed a delay in the longitudinal growth of the tibia, as well as in the growth of all structures enclosed by the perichondrium-periosteum. The cartilage formation rate remained nearly unchanged (above 1 mm3/day) from Day 12 to Day 14, whereas the cartilage resorption rate was zero up to Day 13, and showed a non-significant increase from Day 13 onwards. This might be related to the scarcity of resorptive cells found in the cartilage-marrow interface. By Day 14 a certain recovery of the growth rhythm was observed. These results indicate that the greatest effect of dexamethasone occurs at the level of cartilage resorption.