Steep Increase in Myonuclear Domain Size During Infancy

Authors

  • Tammo Delhaas,

    Corresponding author
    1. Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre+, Maastricht, the Netherlands
    2. Department of Pediatric Cardiology, University Hospital Gasthuisberg, Leuven, Belgium
    • MD, PhD, Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
    Search for more papers by this author
    • Fax: +31 43 388 1725

    • Deceased 28 July 2010.

  • Sander F.T. Van der Meer,

    1. Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, United Kingdom
    Search for more papers by this author
  • Gert Schaart,

    1. NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Movement Sciences, Maastricht University Medical Centre+, Maastricht, The Netherlands
    Search for more papers by this author
  • Hans Degens,

    1. Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester, United Kingdom
    Search for more papers by this author
  • Maarten R. Drost

    1. NUTRIM School for Nutrition, Toxicology and Metabolism, Department of Human Movement Sciences, Maastricht University Medical Centre+, Maastricht, The Netherlands
    Search for more papers by this author

  • Abbreviations used: DAPI = 4′,6-Diamidino-2-phenylindole; FCSA = fiber cross-sectional area; RT = room temperature; SEM = standard error of the mean.

Abstract

We investigated whether myonuclear number increases in proportion to the increase in fiber size during maturational growth of skeletal muscle. Thoraco-abdominal muscle tissue was obtained from twenty 6-day to 15-year-old boys and girls during cardiothoracic surgery. Cross-sections were stained by anti-laminin for the basal lamina and by DAPI to identify nuclei. Basal lamina was traced on digital images to measure the fiber cross-sectional area (FCSA). Nuclei located within the basal lamina were considered myonuclei if pax7-negative and satellite cell nuclei if pax7-positive. Samples of two children were excluded from analysis because of clear signs of hypoxia as shown by positive carbonic anhydrase IX staining. Linear regression showed that FCSA increased with age by 187 μm2·per annum (R2 = 0.90; P < 0.001). Satellite cell density showed a dramatic decrease in the first months of life, but this was not accompanied by an increase in myonuclei per muscle fiber cross-section. Till four years of age the number of myonuclei per muscle fiber cross-section remained relatively constant but increased thereafter. Myonuclear domain size showed a steep increase during infancy and reached adult values in the young adolescent phase. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.

Ancillary