Fig. 8.

T tubule structure reorganization during fiber dedifferentiation. Transmitted light images (average of 8 frames) of FDB fibers cultured in serum-containing media after 1 (A) and 7 (B) days in culture. B and E: laser confocal images (average of 16 frames) of the same fibers stained with pyridinium, 4-[2-(6-(dioctylamino)-2-naphthalenyl) ethenyl]-1-(3-sulfopro-pyl)-, inner salt (di-8-ANEPPS) from a single z-axis plane. C and F: enlarged views of the outlined regions of the fibers shown in B and E, respectively. Red traces, average intensity profile, plotted as a function of the longitudinal position, of area enclosed within white rectangles in B and E. After 7 days in culture, T tubular structure was disorganized and characterized by an apparent reduction in the T tubule spacing.