Figure 3. Mitochondrial morphology in adult and neonatal rat ventricular myocytes.
A. One plane of mitochondria from an adult rat ventricular myocyte, visualized using TMRE under confocal microscope. Mitochondria within the cell are highly organized following patterns of the contractile apparatus. The mitochondria appear as uniform box-like shapes.
B. Mitochondrial morphology of normal neonatal rat ventricular myocytes (Day 3 in culture) visualized by a mitochondrial-targeted red fluorescent protein (mRFP). There are two populations of mitochondria: thin filamentous or large globular. Unlike the adult myocytes, these mitochondria are disorganized and do not appear to be poised for excitation-contraction-metabolism coupling at this stage in development. The mitochondrial morphology may change in development to accommodate increased energy demands of the cell.
C. Mitochondria from adult rat ventricular myocytes that are viewed from a longitudinal slice (left) appear as cylindrical or ovular shaped, whereas mitochondria that are viewed from a transverse slice (right are partially wrapped around myofilaments to different degrees.