Fig. 2. Histology of transgenic mouse hearts. (A) Longitudinal sections of whole mouse hearts of Tg-E22K vs Tg-WT or Non-Tg mice. After euthanasia, the hearts of 13-month-old mice from Non-Tg, Tg-WT and Tg-E22K mice were excised and immersed in 10% buffered formalin. Longitudinal sections of the mouse hearts were stained with hematoxylin and eosin for overall morphology and hypertrophy. Note that the inter-ventricular septum (IVS) of Tg-E22K mice appears more massive than septa of Tg-WT or Non-Tg mice. Also, the papillary muscles of the left ventricles in Tg-E22K hearts appear more substantial than in Tg-WT or Non-Tg mice. (B) Microscopic views of the inter-ventricular septa (upper panels) and left ventricles (lower panels) of Tg-E22K vs Tg-WT or Non-Tg mouse hearts. As indicated, no myofilament disarray was observed in any presented heart tissue. Additionally there was no variation between different mouse lines. LVW, left ventricular wall; IVS, inter-ventricular septum.