A quantitative analysis of cellular and matrix changes in Meckel's cartilage in Xenopus laevis.

The changes in cell population and matrix volume fraction in Meckel's cartilage during metamorphic climax have been assessed using standard stereological techniques. The period of climax has been divided into three phases, a preliminary 'Lag' phase (NF Stages 57-60), a 'Division' phase (NF Stages 60-62) when the cell population rises rapidly and a 'Synthesis' phase (NF Stages 62-66) when the matrix content of the tissue also increases dramatically. These changes along with the membranous ossification occurring at the same time are postulated to be associated with the change in the feeding habit of the larvae from filtration prior to metamorphic climax to active predation in the young frog.