The sub-lip domain--a distinct pathway for myotome precursors that demonstrate rostral-caudal migration.
We have previously reported that the myotome is formed by a first wave of pioneer cells generated from all along the dorsomedial portion of the epithelial somite and a second wave of cells issued from all four edges of the dermomyotome. Cells from the extreme rostral and caudal edges directly generate myofibers that elongate towards the opposite pole of each segment and along the pre-existing myotomal scaffold. In contrast, cells from the dorsomedial and ventrolateral lips first reach the extreme edges and then contribute to myofiber formation. The mechanism by which these epithelial cells translocate remained unknown and was the goal of the present study. We have found that epithelial cells along the dorsomedial and ventrolateral lips of the dermomyotome first delaminate into the immediate underlayer of the corresponding lips, the sub-lip domain, then migrate longitudinally along this pathway until reaching the extreme edges from which they differentiate into myofibers. Cells of the sub-lip domain are negative for Pax3 and desmin but express MyoD, Myf5 and FREK, suggesting that they are specific myogenic progenitors.
Cinnamon
Y
Y
Department of Anatomy and Cell Biology, Hebrew University-Hadassah Medical School, Jerusalem 91120, PO Box 12272, Israel.
Kahane
N
N
Bachelet
I
I
Kalcheim
C
C
D000818:Animals; D002232:Carbocyanines; D002465:Cell Movement; D004268:DNA-Binding Proteins / Q000032:analysis; D003893:Desmin / Q000032:analysis; D004847:Epithelial Cells / Q000166:cytology; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007797:Laminin / Q000032:analysis; D018613:Microscopy, Confocal; D009124:Muscle Proteins / Q000235:genetics; D018482:Muscle, Skeletal / Q000166:cytology* / Q000196:embryology*; D017570:MyoD Protein / Q000235:genetics; D051787:Myogenic Regulatory Factor 5; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D011784:Quail / Q000196:embryology*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D051499:Receptor, Fibroblast Growth Factor, Type 4; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics; D019170:Somites / Q000166:cytology / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology*; D015534:Trans-Activators; D014157:Transcription Factors
C101089:CM-DiI; D002232:Carbocyanines; D004268:DNA-Binding Proteins; D003893:Desmin; D007797:Laminin; D009124:Muscle Proteins; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; D015534:Trans-Activators; D014157:Transcription Factors; C068686:Pax3 protein, mouse; C086864:FGFR4 protein, Coturnix coturnix; D020794:Receptor Protein-Tyrosine Kinases; D051499:Receptor, Fibroblast Growth Factor, Type 4