Cardiomyocytes show evidence of cell hypertrophy at the amputation site.

<p>Cardiomyocytes were observed at the site of amputation (*; see A, C, E, G, I, K and their respective magnifications A’, C’, E’, G’, I’, K’) and in a remote zone of the amputated ventricle (see B, D, F, H, J, L and their respective magnifications B’, D’, F’, H’, J’, L’), using WGA labelling as an indicator of hypertrophy. (A-L) Sections were labelled with WGA (cell membranes, red) and DAPI (nuclei, blue) for different times after amputation (1 & 7 dpa and 1, 6 & 11 mpa) and compared with a control non-amputated heart (CTRL). On the right of each picture, a post treatment of the red/WGA images allows better visualisation of the signal intensity. Note that in the control heart the myocardium showed a comparable level of labelling in the apex or in the remote zone of the ventricle (A, B), with a stronger signal in the epicardium (A). An increase of WGA labelling in the myocardium was evident from 1 mpa to 11 mpa in the vicinity of the amputation site (compare the green colour for G, I, K with C, E), whereas no differences were seen in the remote zone with the CTRL (compare the green colour for D, F, H, J, L with B). (A’-L’) Magnification of a longitudinal view of WGA-labelled cardiomyocytes: control heart showed a thin and regular WGA labelling (A’ and B’) whereas for the amputated heart, an increase of the thickness and the irregularity of the WGA signal was observed from 1 dpa up to 11 mpa compared to the control (A’) or with the WGA signal in the remote zone (see B’, D’, F’, H’, J’, L’). Animals: CTRL, n = 2; 1dpa, n = 1; 7dpa, n = 2; 1mpa, n = 3; 6mpa, n = 2, 11mpa, n = 2. Scale bars, 200 μm (A–L), 20 μm (A’–L’).