Hyaluronate in morphogenesis: inhibition of chondrogenesis in vitro.

Purified hyaluronate, at a concentration as low as 1 ng/ml, blocks the formation of colonies and cartilage nodules in stationary cultures of cells, isolated by treatment with trypsin, from embryonic chick somites and limb buds. This phenomenon in vitro is correlated with sequences of hyaluronate production and hyaluronidase activity during chondrogenesis in embryonic and regenerating tissues in vivo. An hypothesis is proposed in which hyaluronate acts as a regulator or inhibitor of mesenchymal cell aggregation in embryogenesis, its synthesis and removal being part of the mechanism of timing of migration, aggregation, and subsequent differentiation.