We used fluorescently labeled phalloidin to examine the subumbrellar musculature of the scyphozoan jellyfish Aurelia aurita in a developmental series from ephyra to adult medusa. In the ephyra, the swim musculature includes a disc‐like sheet of circular muscle, in addition to two radial bands of muscle in each of the eight ephyral arms. The radial muscle bands join with the circular muscle, and both circular and radial muscle act together during each swim contraction. As the ephyra grows into a juvenile medusa, arms tissue is resorbed as the bell tissue grows outward, so eventually, the ephyral arms disappear. During this process, the circular muscle disc also grows outward and the radial muscle bands of the arms also disappear. At this time, a marginal gap appears at the bell margin, which is devoid of circular muscle cells, but has a loose arrangement of radial muscle fibers. This marginal gap is preserved as the medusa grows, and contributes to the floppy nature of the bell margin. Radial distortions in the circular muscle layer involve muscle fibers that run in random directions, with a primarily radial orientation. These are believed to be remnants of the radial muscle of the ephyral arms, and the distortions decrease in number and extent as the medusa grows. Since the mechanics of swimming changes from drag‐based paddling in the ephyra to marginal rowing in the adult medusa, the development of the marginal gap and the presence of radial distortions should be considered in terms of this mechanical transition.

中文翻译：

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Aurelia aurita Medusae的幼虫，幼虫和成年阶段的伞下肌肉组织

我们使用了荧光标记的鬼笔环肽来检查后生水母水母Aurelia aurita的伞下肌肉组织在从翡翠到成年美杜莎的发育系列中。在腓肠肌中，游泳肌肉组织包括一块圆盘状的环形肌肉，另外八个e肌臂中的每条都有两条放射状的肌肉带。radial肌带与环形肌相连，在每次游泳收缩过程中，环形肌和radial肌共同作用。当e茎长成少年美杜莎时，手臂组织随着钟形组织向外生长而被吸收，因此最终，phy茎臂消失了。在此过程中，环形肌盘也向外生长，手臂的radial肌带也消失了。此时，在钟形边缘处出现边缘间隙，该边缘间隙没有环形肌细胞，但radial肌纤维的排列较松散。随着美杜莎的成长，这一边际差距得以保留，并增加了钟形边距的松散性质。圆形肌层中的径向变形涉及沿随机方向延伸的肌肉纤维，主要是径向方向。这些被认为是腓骨臂the肌的残余物，并且随着水母的生长，畸变的数量和程度减小。由于游泳的力学从在蝇drag中的基于阻力的划桨改变为在成年美杜莎的边缘划船，因此应根据这种机械过渡来考虑边缘间隙的发展和径向变形的存在。随着美杜莎的成长，畸变的数量和程度都会减少。由于游泳的力学从在蝇drag中的基于阻力的划桨改变为在成年美杜莎的边缘划船，因此应根据这种机械过渡来考虑边缘间隙的发展和径向变形的存在。随着美杜莎的成长，畸变的数量和程度都会减少。由于游泳的力学从在蝇drag中的基于阻力的划桨改变为在成年美杜莎的边缘划船，因此应根据这种机械过渡来考虑边缘间隙的发展和径向变形的存在。