Effect of the brachypod mutation on cell adhesion and chondrogenesis in aggregates of mouse limb mesenchyme

Twelve-day normal and brachypod mouse limb mesenchyme was studied in rotation culture. Over a 3£ h period the rate of decline of single cells was significantly greater in mutant than in normal cultures, probably because the brachypod cells were more adhesive. However, the final size of the aggregates and their cell densities were the same by 24 h of incubation. On the other hand their pattern of chondrogenesis was different. Normal aggregates contained condensations with typical histotypic cartilage by 24 h of incubation, and were entirely chondrifled by 4 days in culture. The condensations in brachypod aggregates were fewer, smaller, and delayed in their chondrogenesis. Never more than 50% of the brachypod aggregate exhibited chondrogenesis. The importance of cell contact and cell density to the chondrogenic process are discussed.