mtDNA copy number per diploid nucleus in skeletal muscle and heart of <i>Tk2</i>^+/+ and <i>Tk2</i>^−/− pups at 4, 8 and 14 days after birth.

<p>For each time point, data from at least 3 different mice have been used (<i>n</i>≥3). The <i>P</i>-values for statistical comparisons (two-tailed unpaired Student's t-test) between <i>Tk2</i>^+/+ and <i>Tk2</i>^−/− tissues are shown - *<i>P</i><0.05;</p>**<p><i>P</i><0.01.