File:Mouse- postnatal muscle-extensor digitorum longus.jpg

Satellite cell number steadily decreases from P6, to reach the adult level by P21. ( mouse extensor digitorum longus, EDL)

Satellite cells were identified and counted on isolated Myf5nlacZ/+ and 3F-nlacZ-E myofibres and pooled at each age to give a mean ± SEM (a). The number of satellite cells per myofibre decreased by 0.66 satellite cells per day (R2 = 0.98) to reach the adult level by P21, when it remained unchanged until 10 months, our oldest age analysed. The same data with satellite cells expressed as a percentage of total myofibre nuclei (myonuclei plus satellite cells) (b). Due to the rapidly increasing myonuclear number, there is an exaggerated fall from P6 until P21. Data shown are mean ± SEM (n > 30 myofibres from at least 6 mice at P7, P14, P21 and P56, and at least 2 mice per age at all other stages). White et al. BMC Developmental Biology 2010 10:21 doi:10.1186/1471-213X-10-21

Original file name: 1471-213X-10-21-4.jpg

Dynamics of muscle fibre growth during postnatal mouse development. White RB, Biérinx AS, Gnocchi VF, Zammit PS. BMC Dev Biol. 2010 Feb 22;10:21. PMID: 20175910 | BMC

"Postnatal fast muscle fibre type growth is divided into distinct phases in mouse EDL: myofibre hypertrophy is initially supported by a rapid increase in the number of myonuclei, but nuclear addition stops around P21. Since the significant myofibre hypertrophy from P21 to adulthood occurs without the net addition of new myonuclei, a considerable expansion of the myonuclear domain results. Satellite cell numbers are initially stable, but then decrease to reach the adult level by P21. Thus the adult number of both myonuclei and satellite cells is already established by three weeks of postnatal growth in mouse."

© 2010 White et al; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.