McGeachie J K, Grounds M D, Partridge T A, Morgan J E
Department of Anatomy and Human Biology, University of Western Australia, Nedlands.
J Neurol Sci. 1993 Nov;119(2):169-79. doi: 10.1016/0022-510x(93)90130-q.
Cell replication in muscle was measured by tritiated thymidine (3H-TdR) incorporation and autoradiography, in mdx mice from 2-44 weeks of age. Pre-mitotic labelling (within 1 h of 3H-TdR injection) was determined in 16 mice aged from 15 to 300 days. In 30 further mdx mice, one leg was irradiated 1 h after 3H-TdR injection to block DNA synthesis. Post-mitotic labelling was measured in both legs 10-15 days later. Between 20 and 60 days of age a very high proportion (up to 2%) of muscle (satellite cell) nuclei were replicating pre-mitotically; from 80-300 days cell replication was detectable but at much lower levels. Centrally placed nuclei within muscle fibres appeared at 24 days, increased rapidly to 50% by 50-100 days, declining thereafter to 25% at 300 days. In post-mitotic samples, labelled myotubes and labelled peripheral muscle nuclei (satellite cell nuclei and myonuclei) appeared at 28 days and were present in the mdx muscles through to 310 days, indicating continued cell replication and muscle regeneration. Myogenic cell replication was both retarded and inhibited by irradiation. These data demonstrate that muscle cell replication in mdx mice commences at about 3 weeks of age, is maximal at 4-8 weeks, but continues at lower levels until at least 44 weeks.
通过氚标记胸腺嘧啶核苷（3H-TdR）掺入和放射自显影技术，对2至44周龄的mdx小鼠的肌肉细胞复制进行了测量。在16只15至300日龄的小鼠中测定了有丝分裂前标记（3H-TdR注射后1小时内）。在另外30只mdx小鼠中，在3H-TdR注射后1小时对一条腿进行照射以阻断DNA合成。10至15天后在两条腿上测量有丝分裂后标记。在20至60日龄之间，非常高比例（高达2%）的肌肉（卫星细胞）核进行有丝分裂前复制；从80至300日龄可检测到细胞复制，但水平要低得多。肌肉纤维内位于中央的核在24天时出现，到50至100天时迅速增加到50%，此后在300天时下降到25%。在有丝分裂后样本中，标记的肌管和标记的外周肌肉核（卫星细胞核和肌细胞核）在28天时出现，并在mdx肌肉中一直存在至310天，表明细胞持续复制和肌肉再生。成肌细胞复制受到照射的延迟和抑制。这些数据表明，mdx小鼠的肌肉细胞复制在约3周龄时开始，在4至8周时达到最大，但以较低水平持续至至少44周。
