Epithelial-mesenchymal interaction in the regulation of hyaluronate production during limb development

Cocultures of ectoderm and mesoderm from chick limb buds produced 1.5 to 2.5-fold more hyaluronate than the sum of that produced by epithelium and mesoderm cultures grown separately. Mesoderm incubated with conditioned medium prepared from cultures of limb ectoderm synthesized 2.5-fold more hyaluronate. The increase in hyaluronate was not due to a stimulation of cell proliferation, nor was there increased incorporation into total protein or chondroitin sulfate. These results suggest that in the developing limb the ectoderm may influence the subjacent mesoderm to maintain a relatively high rate of hyaluronate synthesis, resulting in a peripheral limb bud matrix enriched in hyaluronate.