Figure 7. Time course of Pax7 expression in the mouse. (A–D) Pax7 mRNA expression from E9.5-E12.5 of development; lateral views of the right side of embryos, anterior to the top. Expression is readily detectable in the developing central nervous system, emigrating neural crest cells (prolonged expression in the frontonasal neural crest) and the somites. Head muscle anlagen show expression first at E10.5. (E) Serial cross sections of the mandibular arch at E12.5, dorsal to the top; (F,G) higher magnifications of the areas indicated by the boxes in (E) and stained for Dapi and MyoD protein (Fi,ii) or Dapi and Pax7 protein (Gi,ii). Note that MyoD and Pax7 domains overlap. (H,I) Serial frontal sections of the mandible at birth (P0), dorsal to the top, lateral to the left. (H) Sirius Red staining showing muscle fibers in yellow and bone and connective tissue in red. (I) Dapi staining of the same region, with (Ii) showing a magnification of the cheek and the floor of the mouth as indicated in (I). Skeletal muscle fibers are shown in red. (J) Subsequent section stained for Pax7 protein in red. Note the punctate, nuclear staining for Pax7, associated with the Myosin-positive muscle fibers. (K–Q) Lineage tracing of Pax7 expressing cells, revealed by beta galactosidase staining; lateral views of the right side of embryos, dorsal to the top. With a delay of 1 day, cells with a history of Pax7 expression can be detected in the central nervous system, the trigeminal ganglion, the frontonasal neural crest and the somites. In craniofacial muscle anlagen, cells with a history of Pax7 expression can be detected between E11.5 and E12.5, with a more robust staining appearing at E13.5. Eventually, all craniofacial muscles are stained and the staining is found in muscle fibers, indicating that, similar to the trunk, Pax7-positive cells contribute to fetal and perinatal muscle growth. Abbreviations as in Figures 1, 3, 4 and: fl, forelimb; ISH, in situ hybridisation; ms, masseter; te, temporalis muscle; wt, wildtype.
Image published in: Nogueira JM et al. (2015)
Copyright © 2015 Meireles Nogueira, Hawrot, Sharpe, Noble, Wood, Jorge, Goldhamer, Kardon and Dietrich. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license
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