The objective of the current study is to present data on the
splitting of skeletal muscle fibers in C57BL/6NCrl mice. Skeletal
muscles (m. rectus femoris (m. quadriceps femoris)) from 500
(250 ♀ and 250 ♂) C57BL/6NCrl mice in the 16th week of life
were sampled during autopsy and afterwards standardly
histologically processed. Results show spontaneous skeletal
muscle fiber splitting which is followed by skeletal muscle fiber
regeneration. One solitary skeletal muscle fiber is split, or is in
contact with few localized splitting skeletal muscle fibers. Part of
the split skeletal muscular fiber is phagocytosed, but the
remaining skeletal muscular fiber splits are merged into one
regenerating skeletal muscle fiber. Nuclei move from the
periphery to the regenerating skeletal muscle fiber center during
this process. No differences were observed between female and
male mice and the morphometry results document <1 % skeletal
muscle fiber splitting. If skeletal muscular fibers splitting occurs
5 %> of all skeletal muscular fibers, it is suggested to describe
and calculate this in the final histopathological report.