QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kahane, N. Articles by Kalcheim, C. Search for Related Content PubMed PubMed Citation Articles by Kahane, N. Articles by Kalcheim, C.

The third wave of myotome colonization by mitotically competent progenitors: regulating the balance between differentiation and proliferation during muscle development

Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, PO Box 12272, Israel

*Author for correspondence (e-mail: kalcheim{at}yam-suff.cc.huji.ac.il)

Accepted March 26, 2001

The myotome is formed by a first wave of pioneer cells originating from the entire dorsomedial region of epithelial somites and a second wave that derives from all four lips of the dermomyotome but generates myofibers from only the rostral and caudal edges. Because the precedent progenitors exit the cell cycle upon myotome colonization, subsequent waves must account for consecutive growth. In this study, double labeling with CM-DiI and BrdU revealed the appearance of a third wave of progenitors that enter the myotome as mitotically active cells from both rostral and caudal dermomyotome edges. These cells express the fibroblast growth factor (FGF) receptor FREK and treatment with FGF4 promotes their proliferation and redistribution towards the center of the myotome. Yet, they are negative for MyoD, Myf5 and FGF4, which are, however, expressed in myofibers.

The proliferating progenitors first appear around the 30-somite stage in cervical-level myotomes and their number continuously increases, making up 85% of total muscle nuclei by embryonic day (E)4. By this stage, generation of second-wave myofibers, which also enter from the extreme lips is still under way. Formation of the latter fibers peaks at 30 somites and progressively decreases with age until E4. Thus, cells in these dermomyotome lips generate simultaneously distinct types of muscle progenitors in changing proportions as a function of age. Consistent with a heterogeneity in the cellular composition of the extreme lips, MyoD is normally expressed in only a subset of these epithelial cells. Treatment with Sonic hedgehog drives most of them to become MyoD positive and then to become myofibers, with a concurrent reduction in the proportion of proliferating muscle precursors.

Key words: Avian embryo, Dermomyotome, FGF, FREK, Muscle satellite cells, MyoD, Myf5, Myogenesis, PAX, Pioneer myotomal cells, Proliferation, Sclerotome, Somite, Sonic hedgehog, Stem cells, Quail

This article has been cited by other articles:

				S. J. Venters and C. P. Ordahl Persistent myogenic capacity of the dermomyotome dorsomedial lip and restriction of myogenic competence Development, March 10, 2003; 129(16): 3873 - 3885. [Abstract] [Full Text] [PDF]

				I. Marics, F. Padilla, J.-F. Guillemot, M. Scaal, and C. Marcelle FGFR4 signaling is a necessary step in limb muscle differentiation Development, January 10, 2002; 129(19): 4559 - 4569. [Abstract] [Full Text] [PDF]

				N. Kahane, Y. Cinnamon, and C. Kalcheim The roles of cell migration and myofiber intercalation in patterning formation of the postmitotic myotome Development, January 6, 2002; 129(11): 2675 - 2687. [Abstract] [Full Text] [PDF]