Fig. 6: PSMAD1/5/9+ myonuclei label two myonucleus populations of distinct embryological origins at muscle tips.
From: Unexpected contribution of fibroblasts to muscle lineage as a mechanism for limb muscle patterning
a Schematic of isotopic presomitic mesoderm grafts from quail to chicken embryos. b Longitudinal view of a limb muscle from E6 chimera labelled with pSMAD1/5/9 (green), QCPN (quail nuclei, red) and MF20 (myosins, grey) antibodies, with a focus on muscle tips. c Adjacent section to b labelled with COLXII (tendon, green), QCPN (quail nuclei, red) and MF20 (myosins, grey) antibodies. d Focus on muscle tips, labelled with pSMAD1/5/9 (green), QCPN (quail nuclei, red) and MF20 (myosins, grey) antibodies, combined with DAPI (blue). White arrows point to pSMAD1/5/9+ myonuclei (green) that are not of quail origin (QCPN−), while yellow arrows point to pSMAD1/5/9+ myonuclei (green) that are of quail origin (QCPN+, red). e Transverse view of the FCU muscle from E9 chimera labelled with pSMAD1/5/9 (green), QCPN (quail nuclei, red) and MF20 (myosins, grey) antibodies. f Adjacent section to e labelled with COLXII (tendon, green), QCPN (quail nuclei, red) and MF20 (myosins, grey) antibodies, combined with DAPI. g Focus on muscle tips. White arrows point to pSMAD1/5/9+ myonuclei (green) that are not of quail origin (QCPN−), while yellow arrows point to pSMAD1/5/9+ myonuclei (green) that are of quail origin (QCPN+, red).
