Fig. 6. The dorsalmost region of the desmin-positive myotome contains unit-length myofibers, with myofiber generation primarily beginning from the extreme edges of the dermomyotome. (A-C) The dorsomedial-most desmin-positive fibers detected in the myotome are anchored to both extremes of the segment. The central nucleus-containing area is less stained and no partial fibers can be visualized approaching the DML. DiI applied to the rostral extreme of a segment (asterisk) diffused along the fibers until reaching their caudal end (arrows in B,C). Co-localization of DiI and desmin staining define that dorsalmost fibers are of full length and highlight the absence of partial-length fibers. (D) Elongating fibers (between arrows and arrowheads) emerge from an extreme lip adjacent to the intersomitic region (IS, and broken line separating adjacent segments). Notably, unit length fibers had broad end-feet attached to the edges, whereas growing fibers demonstrated tapered attachments.
