Differential survival of cartilage and muscle cells in chick limb-bud cell cultures maintained in chemically defined and serum-containing media.

Chick limb buds at stages 22-23 largely consist of replicating presumptive chondroblasts and presumptive myoblasts. To study the influence that different medium compositions may have on the survival, replication, and terminal differentiation of these dissociated cells in vitro, micromass cultures were reared in either standard Dulbecco's modified Eagle's medium containing fetal calf serum (SC-DMEM) or in serum-free DMEM. By day 4, approximately 80% and 50% of the original cell inoculum had been lost in DMEM and SC-DMEM cultures, respectively, as estimated from the recovery of incorporated 3H-thymidine. Between days 1 and 4, the total-DNA content remained virtually constant in DMEM cultures, while it increased five- to sixfold in SC-DMEM cultures. In both media, definitive myoblasts and chondroblasts first emerged on day 1 and day 2, respectively, as determined by immunofluorescence staining using antibodies against muscle light meromyosin (LMM) or the major cartilage proteoglycan. In both media, the chondroblasts increased in number and, by day 4, had formed sizable chondroblast nodules. The number of chondroblasts in SC-DMEM cultures exceeded that observed in DMEM cultures. In DMEM, the LMM-positive myoblasts had an atypical morphology and failed to fuse into elongated myotubes; these cells began to degenerate on about day 4, being undetectable by day 8. In SC-DMEM, the numerous LMM-positive myoblasts located in the center of the micromasses also had an atypical morphology, failed to form multinucleated myotubes, and were absent by day 8.(ABSTRACT TRUNCATED AT 250 WORDS)