Capillary network of skeletal muscle has a crucial role in oxygen supply and is strongly associated with the phenotype and metabolic profile of muscle fibers. Abundant literature has explored capillarization of skeletal muscle in different populations and in response to different interventions. Capillary and fiber type identification techniques have considerably evolved over the last decades, but to the best of our knowledge, no validated immunohistochemical method has yet been developed to simultaneously identify capillaries (using CD31), the three different muscle fiber types, and basal lamina. Nine human muscle biopsies of vastus lateralis were stained using 5 different methods to test: the reliability of different CD31 antibodies for capillary identification, the reliability between single-section or serial-section methods, and the intra-experimenter reproducibility in visual detection of capillaries. High reliability for the different antibodies directed against capillaries was observed for capillary contacts (CC) measurements (intra-class correlations (ICC) [ICC_95%] of 0.89 [0.72; 0.96] for type I fibers, 0.93 [0.81; 0.97] for type IIA fibers, 0.88 [0.71; 0.96] for type IIX fibers, 0.95 [0.86; 0.98] for all fiber types) as well as a high level of similarity between single and serial sections methods. A strong similarity in capillary analysis between the different methods was obtained for each sample measurements. Analysis of Lin’s concordance correlation coefficients and Bland and Altman’s graphics showed a strong intra-experimenter reproducibility. This article proposes two time- and tissue-sparing immunohistochemical methods to accurately assess a complete fiber typing (type I, IIA, and IIX) along with muscle capillarization on a single muscle section.

骨骼肌的毛细血管网络在氧气供应中起着至关重要的作用，并且与肌纤维的表型和代谢谱密切相关。大量文献探讨了不同人群中骨骼肌的毛细血管化以及对不同干预措施的反应。在过去的几十年中，毛细管和纤维类型识别技术得到了长足的发展，但据我们所知，尚未开发出经过验证的免疫组织化学方法来同时识别毛细血管（使用CD31），三种不同的肌肉纤维类型和基底层。九名人类股外侧肌活检使用5种不同的方法对细胞进行染色以测试：用于毛细血管识别的不同CD31抗体的可靠性，单切片或连续切片方法之间的可靠性以及毛细血管视觉检测中实验内的可重复性。在毛细管接触（CC）测量中，观察到了针对毛细血管的不同抗体的高可靠性（类内相关性（ICC）[ICC _95％]为0.89 [0.72; I型纤维为0.93 [0.81； 0.96]；IIA型纤维为0.98]，0.88 [0.71; 对于IIX型纤维，为0.95 [0.86; 0.98]（适用于所有光纤类型），以及单段和串行段方法之间的高度相似性。每次样品测量均获得了不同方法之间毛细管分析的高度相似性。Lin的一致性相关系数以及Bland和Altman的图形的分析显示出强大的内部实验再现性。本文提出了两种节省时间和组织的免疫组织化学方法，以准确评估完整的纤维类型（I型，IIA和IIX型）以及单个肌肉切片上的毛细血管化。