XB-ART-26837Dev Biol 1989 Apr 01;1322:529-43. doi: 10.1016/0012-1606(89)90248-0.
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Amphibian (urodele) myotomes display transitory anterior/posterior and medial/lateral differentiation patterns.
Myotome differentiation during Mexican axolotl (Ambystoma mexicanum) somitogenesis was analyzed by employing anti-actin and anti-myosin monoclonal antibodies as molecular probes. Myotome differentiation occurs after segmentation and proceeds in the cranial-to-caudal direction along the somite file. Within individual somites myotome differentiation displays distinct polarities. Examination of the somite file at the tailbud stage revealed that soon after segmentation, actin/myosin accumulate predominantly in the anterior and medial region of the myotome initially. Subsequently, cells within the myotome differentiate in an anterior-to-posterior and medial-to-lateral direction. Experimental analysis of presomitic paraxial mesoderm grafts before segmentation revealed that this transient myotome polarity is autonomous. Comparative analyses indicate that this myotome differentiation pattern is urodele specific. Cynops pyrrhogaster undergoes myotome differentiation like the axolotl, while two anurans, Xenopus laevis and Bombina orientalis, do not.
PubMed ID: 2647546
Article link: Dev Biol
Species referenced: Xenopus laevis
Genes referenced: acta4 actl6a elavl3
Antibodies: Act3 Ab2 Somite Ab1
Article Images: [+] show captions
|FIG. 9. Xenopus stage 27/28 whole mount stained with HUC l-l anti-actin MoAb. (A) Cranial-to-caudal concentration gradient of actin accumulation is easily recognized (19X). No anterior/posterior intramyotomal polarity is, however, detected. (B-D) Successive enlargements of the caudal region, where segmentation is occurring: (B) 48X, (C) 96X, (D) 191X. Myoblasts in all stages of the reorientation process which accompanies segmentation stain. (C) The myoseptal borders stain more intensely (arrow) than the central regions of the myotomes, an observation which was confirmed by staining conventional histological sections (data not shown). Upper somite file adjacent to the slide (arrowhead) compacted during processing. (D) The nonsegmented presomitic mesenchyme (arrows) stains. nc, notochord. Bars = (A) 1 mm, (B) 200 um, (C) 100 um, and (D) 100 um.|