van Raamsdonk W, Mos W, Tekronnie G, Pool C W, Mijzen P
Acta Morphol Neerl Scand. 1979 Dec;17(4):259-73.
The development of the shape and structure of somites in the teleost Brachydanio rerio was studied in embryos under normal conditions and in immobilized embryos. Three different immobilization methods were applied: enclosure in agar, a glass rod in the neural tube and anaesthesia in MS-222. When the performance of the lateral body movements is prevented, the shape development of the somites in embryos and young larvae becomes reversed. When the agar-immobilization is terminated, the larvae resume their normal movements. In about 10 days, the shape of the somites is again as in control larvae. We conclude, that the lateral body movements have both a shape-determining and a shape-stabilizing role during the early stages of somite morphogenesis. It is suggested that in normal embryos differences in shortening between lateral and medial muscle fibres, cause differences in longitudinal growth of the muscle fibres and that the oblique muscle fibre arrangement is a consequence of these differences in growth. In immobilized embryos and larvae, the longitudinal growth of the muscle fibres is decreased. Also the difference in the longitudinal growth rate between lateral and medial muscle fibres diminishes in all somites. We conclude that for the normal morphogenesis of the somites the performance of the specific function, that is to bring about lateral body movements, is required. We suggest, that the impact of the lateral body movements on the development of the structure of the somites is mediated through adaptive growth of the muscle fibres. The suggestion may also apply to the development of the pinnate structure of muscles of higher vertebrates.
在正常条件下的胚胎以及固定化胚胎中，研究了硬骨鱼斑马鱼体节的形状和结构发育。采用了三种不同的固定化方法：包埋在琼脂中、在神经管中插入玻璃棒以及用MS-222麻醉。当阻止身体侧向运动时，胚胎和幼体中体节的形状发育会发生逆转。当终止琼脂固定化时，幼体恢复正常运动。大约10天后，体节的形状再次与对照幼体相同。我们得出结论，在体节形态发生的早期阶段，身体侧向运动具有形状决定和形状稳定的作用。有人提出，在正常胚胎中，外侧和内侧肌纤维缩短的差异会导致肌纤维纵向生长的差异，并且斜向肌纤维排列是这些生长差异的结果。在固定化的胚胎和幼体中，肌纤维的纵向生长减少。而且，在所有体节中，外侧和内侧肌纤维纵向生长速率的差异也减小了。我们得出结论，为了体节的正常形态发生，需要执行特定功能，即引起身体侧向运动。我们提出，身体侧向运动对体节结构发育的影响是通过肌纤维的适应性生长介导的。该提议也可能适用于高等脊椎动物肌肉羽状结构的发育。
