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Fig. 1
Ventricular apex amputation induces up-regulation of Notch receptor expression in endocardial and epicardial cells. Representative histological sections of uninjured (A, E, I, and M) and injured hearts (B, F, J, and N) at 7 d postamputation (dpa) showing up-regulation of three Notch receptors in the endocardium and/or epicardium following amputation injury by colormetric in situ hybridization analyses. Boxed regions of B, F, J, and N are shown at higher magnifications in C, G, K, and O. (D, H, L, and P) Representative cardiac sections from Tg(kdrl:mCherry) zebrafish processed for fluorescent in situ hybridization to visualize expression of the indicated Notch receptors and mCherry immunohistochemistry to visualize endocardial cells. Notch1a, notch1b, notch2, and notch3 transcripts colocalized with endocardial cells without expression in the intervening myocardium. (M and N) Notch3 transcripts were unchanged by injury. Consistent staining patterns were observed in eight hearts per experimental group for the colorimetric analyses and in two hearts for the fluorescent analyses.