CHONDROGENIC DIFFERENTIATION OF LIMB BUD CELLS IN COLLAGEN GEL CULTURE

Chick limb bud mesenchyme cells were isolated from stage 22-23 embryos and embedded within exogenous collagen gels at low cell density. They grew to form a colony of round cells in situ and differentiated into cartilage with an overt metachromatic matrix. Synthesis of sulfated glycosaminoglycan increased markedly with time and most were deposited within the collagen gel matrix. The cells primarily synthesized type I collagen followed by predominant synthesis of cartilage-specific type II collagen, during the collagen gel culture. The control cells seeded in the monolayer cultures at the same initial density never showed chondrogenic activity. The results indicate that the three-dimensionally enclosed environment of collagen gel culture is required for the limb bud mesenchyme cells to effectively accumulate synthesized matrix macromolecules and to differentiate into cartilage.