Cellular heterogeneity in the chick wing mesoblast. I. Analysis by equilibrium density gradient centrifugation

An analytic and preparative cell separation technique, equilibrium density gradient centrifugation, has been applied to the heterogeneous cell population of the developing chick wing mesoblast in an effort to isolate separately and characterize cell populations differing in buoyant density. When dissociated cell suspensions are distributed throughout a continuous bovine plasma albumin-balanced salt solution gradient and centrifuged to equilibrium, reproducible patterns characteristic of the tissue source or developmental stage of origin are obtained. Such patterns differ both qualitatively and quantitatively. More than 90% of the centrifuged cells remain viable as judged by dye exclusion, and nearly 90% are recovered from the gradients. Cellular subpopulations prepared on these gradients can be cloned yielding cartilage, muscle, or fibroblastic colonies. At stage 25 there appears a population of cells with a mean buoyant cell density of 1.0437 g-cm⁻³ which exhibits a markedly enhanced ability to form cartilage-making clones when compared to cells of differing density or developmental age.