Fig. 3. Effects of FB1 on the fusion of AVP-treated L6 cells. (A) L6 cells were treated without (control) or with 10^-7 M AVP alone, or with the concomitant addition of 20 µM FB1 for 2 days. The cells were examined by phase contrast microscopy. Magnification, 32x; bar, 50 µm. Myogenic differentiation was evidenced by the formation of multinucleated myotubes. (B) The cells treated as above were examined at different times, and the fusion index was evaluated as detailed in the Materials and Methods.