Targeted misexpression of pCAB- Spry2 -Cterminal results in increased number of mitotic cells in the dermomyotome and myotome. (A-Aiii) Brightfield and fluorescent images of the electroporated control side. (B-Biii) Brightfield and fluorescent images of pCAB-Spry2-Cterminal injected and electroporated somites. (A, B) Increased MyoD expression was detected by in situ hybridization (purple) in the injected/electroporated side in (B) with GFP detected in red. (Ai, Bi) Sections were stained with DAPI and dermomyotome and myotome boundaries are indicated with dotted white lines. (Aii, Bii) Immunostaining with anti-Phospho-Histone-H3 detects mitotic cells and shows an increase of the number of the dividing cells in injected dermomyotome and myotome (Bii, within the dotted white lines) in comparison to the contralateral control somite in (Aii). (Aiii, Biii) merged images of DAPI in (Ai, Bi) and Phospho-Histone-H3 stained sections in (Aii, Bii). Maginfications: 200x in all sections. (C). Statistical analysis of the anti-Phospho-Histone-H3 proliferation assay for pCAB-Spry2-Cterminal. Columns represent results of the SPSS statistical analysis of the proliferating cells in myotomes and dermomyotomes of uninjected somites (blue column, control) and in pCAB-Spry2-Cterminal electroporated somites (red column). The analysis confirmed that the differences in the means of paired counting (n=94) of the proliferating myocyte cells were statistically significant (p < 0.002), the diagram shows a graphical representation of these data. Error bars represent the standard deviation .