Abstract
Analysis of embryonic fibroblasts from GFP reporter mice indicates that the fibroblast cell type harbors a large collection of developmentally and phenotypically heterogeneous subtypes. Some of these cells exhibit multipotency, whereas others do not. Multiparameter flow cytometry analysis shows that a large number of distinct populations of fibroblast-like cells can be found in cultures initiated from different embryonic organs, and cells sorted according to their surface phenotype typically retain their characteristics on continued propagation in culture. Similarly, surface phenotypes of individual cloned fibroblast-like cells exhibit significant variation. The fibroblast cell class appears to contain a very large number of denumerable subtypes.