2026-01-13 東京大学
マクラギヤスデ幼体の体節の追加に伴う形態形成過程
<関連情報>
- https://www.s.u-tokyo.ac.jp/ja/press/11039/
- https://link.springer.com/article/10.1186/s13227-025-00257-3
ヤスデ(Niponia nodulosa)の変態期における体節追加に伴う表皮陥入と筋肉再配置 Epidermal invagination and muscle rearrangement associated with the segment addition during anamorphosis in a millipede, Niponia nodulosa
Soma Chiyoda,Kohei Oguchi,Hitoshi Aonuma & Toru Miura
Developmental Biology Advances Published:04 January 2026
DOI:https://doi.org/10.1186/s13227-025-00257-3
We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.
Abstract
Background
Arthropod segmentation involves not only embryonic patterning but also postembryonic segment addition through molting, a process known as anamorphosis. In millipedes (class Diplopoda), which universally undergo anamorphosis, new segmental units also known as “rings” are added anterior to the telson, yet the morphogenetic mechanisms underlying this process remain poorly understood. Here, we investigate ring addition during anamorphosis in the millipede Niponia nodulosa (Polydesmida, Cryptodesmidae), focusing on epidermal and muscular organization. Using X-ray micro-computed tomography and microscopic histological analysis, we reconstructed the sequence of tissue changes preceding molting.
Results
Our results show that a local invagination of the epidermis between the telson and the penultimate ring establishes a ring primordium, whose subsequent development gives rise to a new ring. In stadia where multiple rings are added with one molt, a corresponding number of ring primordia appeared. In addition, the muscle originally linking the penultimate ring to the telson detaches and reattaches to the newly added ring, while additional muscles differentiate within the new ring to form novel connections with the telson. These coordinated changes occur rapidly before molting, enabling ring addition within the restricted posterior body region.
Conclusions
We provided a detailed three-dimensional description of the morphological changes accompanying ring addition. Epidermal morphogenesis and muscular rearrangement are thought to enable the addition of new rings while maintaining the functional integrity of the posterior body, including defecation. This study establishes a histological and morphological basis for understanding segmentation during postembryonic development in arthropods and paves the way for future developmental investigations.
