Arthropods gradually change their forms through repeated molting events during postembryonic development. Anamorphosis, i.e., segment addition during postembryonic development, is seen in some arthropod lineages. In all millipede species (Myriapoda, Diplopoda), for example, postembryonic processes go through anamorphosis. Jean-Henri Fabre proposed 168 years ago the “law of anamorphosis”, that is, “new rings appear between the penultimate ring and the telson” and “all apodous rings in a given stadium become podous rings in the next stadium”, but the developmental process at the anamorphic molt remains largely unknown. In this study, therefore, by observing the morphological and histological changes at the time of molting, the detailed processes of leg- and ring-addition during anamorphosis were characterized in a millipede, Niponia nodulosa (Polydesmida, Cryptodesmidae). In the preparatory period, a few days before molting, scanning electron microscopy, confocal laser scanning microscopy, and histological observations revealed that two pairs of wrinkled leg primordia were present under the cuticle of each apodous ring. In the rigidation period, just prior to molt, observations of external morphology showed that a transparent protrusion was observed on the median line of the ventral surface on each apodous ring. Confocal laser scanning microscopy and histological observations revealed that the transparent protrusion covered by an arthrodial membrane contained a leg bundle consisting of two pairs of legs. On the other hand, ring primordia were observed anterior to the telson just before molts. Preceding the anamorphic molt in which two pairs of legs are added on an apodous ring, a transparent protrusion containing the leg pairs (a leg bundle) appears on each apodous ring. The morphogenetic process of the rapid protrusion of leg bundles, that is enabled by thin and elastic cuticle, suggested that millipedes have acquired a resting period and unique morphogenesis to efficiently add new legs and rings.

中文翻译：

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在千足虫 Niponia nodulosa 变形蜕皮之前的无足环上出现一个透明突起，其中包含两对腿

节肢动物在胚后发育过程中通过反复蜕皮事件逐渐改变其形态。在一些节肢动物谱系中可以看到变形，即在胚后发育过程中增加片段。例如，在所有千足虫物种（多足纲、双足纲）中，胚后过程都会经历变形。让-亨利·法布尔在 168 年前就提出了“变形法则”，即“倒数第二个环和尾节之间出现新的环”和“一个给定体育场的所有足环都变成下一个体育场的足环”，但变形蜕皮的发育过程在很大程度上仍然未知。因此，在这项研究中，通过观察蜕皮时的形态学和组织学变化，在千足虫中描述了变形过程中腿部和环部添加的详细过程，Niponia nodulosa (Polydesmida, Cryptodesmidae)。在准备期，即蜕皮前几天，扫描电子显微镜、共聚焦激光扫描显微镜和组织学观察表明，在每个足环的角质层下存在两对皱纹腿原基。在硬化期，即蜕皮之前，对外部形态的观察表明，在每个无足环的腹面中线上观察到透明突起。共聚焦激光扫描显微镜和组织学观察表明，被关节膜覆盖的透明突起包含一个由两对腿组成的腿束。另一方面，在蜕皮之前，在尾节之前观察到环状原基。在变形蜕皮之前，在无足环上添加了两对腿，每个无足环上出现了一个包含腿对（腿束）的透明突起。由薄而有弹性的角质层促成的腿束快速突出的形态发生过程表明，千足虫已经获得了一个休息期和独特的形态发生，可以有效地增加新的腿和环。