Figure 1

Shh induces terminal differentiation and slow MyHC in wing primary cultures. Dissociated cells HH22 wing bud cells were plated at low or high density and grown for two days in the absence (white bars) or presence of Shh-conditioned medium (ShhQT6 CM, black bars) or control CM (QT6 CM, grey bars) and the number of total (A), desmin-reactive (B), pan-MyHC-reactive (C) and slow MyHC-reactive (D) cells determined. Data from two low and one high density experiment are presented (mean ± SEM, derived by addition of fractional errors, numbers above columns are dishes for the numerator). A. Irrespective of plating density, the number of cells in dishes exposed to Shh was ~70% greater than that of control dishes. B. The proportion of desmin-expressing myogenic cells was unchanged by Shh, at either low or high cell density. Note that the proportion of myogenic cells declined at high density, consistent with faster proliferation of non-myogenic cells. C. The proportion of differentiated myogenic cells (defined as the fraction of nuclei within desmin-containing cytoplasm that were in MyHC-containing cytoplasm) increased with Shh, irrespective of density. D. With Shh more differentiated cells express slow MyHC (defined as the fraction of nuclei within MyHC-containing cytoplasm that were in slow MyHC-containing cytoplasm). Note that even the high density culture has more total slow MyHC expressing cells because the same proportion of an increased number of differentiated cells express slow MyHC. ** P ≤ 0.002 compared to control(s), t-test on cell numbers after correcting for change in numerator.