DIVERSIFICATION OF THE MYOFIBRILLAR M-BAND IN RAT SKELETAL-MUSCLE DURING POSTNATAL-DEVELOPMENT
DIVERSIFICATION OF THE MYOFIBRILLAR M-BAND IN RAT SKELETAL-MUSCLE DURING POSTNATAL-DEVELOPMENT
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DOI：
10.1007/bf01239978
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发表时间：
1987-01-01
影响因子：
3.6
通讯作者：
THORNELL, LE
中科院分区：
文献类型：
--
作者：
CARLSSON, E;THORNELL, LE
采用电镜技术研究了新生大鼠和4周龄大鼠比目鱼肌（SOL）和指长伸肌（EDL） m波段的精细结构。在新生大鼠中，两种肌肉中的所有肌管和纤维具有相同的肌原纤维外观。纵截面呈5线m波段，横截面呈明显的m桥。z盘为中等宽度。另一方面，在四周大鼠中，根据其肌原纤维模式观察到不同的肌纤维类型。在SOL中，两种纤维类型在纵剖面上被区分开来。一种有四条线的m波段图案和非常宽的z型圆盘，而另一种有五条线的m波段和宽的z型圆盘。在EDL中，观察到三种不同的肌原纤维模式。m波段由三条、四条或五条线组成。纤维的z盘宽度分别为薄、宽或中等。在SOL肌肉的横截面上，一组纤维显示不明显的m -桥，而在其他纤维和所有观察到的EDL肌肉纤维中都可以看到明显的m -桥。我们的结论是，最初似乎有一个m波段形成的内在程序；这个程序在诱导功能分化的纤维时被修改。
The fine structure of the M-band in soleus (SOL) and extensor digitorum longus (EDL) muscles in newborn and four-week-old rats was studied using electron-microscopic techniques. In newborn rats, all myotubes and fibres in both muscles had an identical myofibrillar appearance. A five-line M-band pattern was seen in longitudinal sections and distinct M-bridges in cross-sections. The Z-discs were of medium width. On the other hand, in four-week-old rats, different muscle fibre types were observed on the basis of their myofibrillar pattern. In SOL two fibre types were distinguished in longitudinal sections. One had a four-line M-band pattern and very broad Z-discs, whereas the other type had five lines in the M-band and broad Z-discs. In EDL, three different myofibrillar patterns were observed. The M-bands were composed of three, four or five lines. Fibres had either thin, broad or medium Z-disc widths, respectively. In cross-sections of the SOL muscle one group of fibres showed indistinct M-bridges, whereas distinct M-bridges were seen in the other fibres and in all observed EDL muscle fibres. We conclude that initially there seems to be a single intrinsic program for M-band genesis; this program becomes modified upon the induction of functionally differentiated fibres.