Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, the Netherlands.
Anat Rec (Hoboken). 2013 Feb;296(2):192-7. doi: 10.1002/ar.22631. Epub 2012 Dec 4.
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 μm(2) ·per annum (R(2) = 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.
我们研究了在骨骼肌成熟生长过程中，肌核数目是否与纤维尺寸的增加成比例增加。在心胸外科手术中，我们从 20 名 6 天至 15 岁的男孩和女孩中获取了胸腹部肌肉组织。通过抗层粘连蛋白对基底膜进行染色，并通过 DAPI 识别核。在数字图像上追踪基底膜以测量纤维横截面积（FCSA）。如果 pax7 为阴性且位于基底膜内的核为肌核，如果 pax7 为阳性且位于基底膜内的核为卫星细胞核。由于阳性碳酸酐酶 IX 染色显示出明显的缺氧迹象，两个孩子的样本被排除在分析之外。线性回归显示 FCSA 每年增加 187μm²（R²=0.90；P<0.001）。卫星细胞密度在生命的头几个月急剧下降，但这并没有伴随着每个肌纤维横截面上肌核的增加。直到 4 岁，每个肌纤维横截面上的肌核数量相对保持不变，但此后增加。肌核域大小在婴儿期急剧增加，并在青少年期达到成人值。
