DATE2026.01.13 #Press Releases
Three-Dimensional Elucidation of Segment Addition in Millipedes
-Visualization of Epidermal Invagination and Muscle Rearrangement Accompanying New Segment Formation-
Summary
A research team led by Professor Toru Miura and Associate Professor Kohei Oguchi of the Misaki Marine Biological Station, Graduate School of Science, The University of Tokyo, together with Graduate Student Soma Chiyoda, and Professor Hitoshi Aonuma of the Graduate School of Science, Kobe University, has revealed in detail the process by which body segments are added during molting in the millipede, Niponia nodulosa, a species that can be easily collected in urban parks.
Millipedes (Phylum Arthropoda, Subphylum Myriapoda, Class Diplopoda; hereafter referred to as millipedes) exhibit a developmental mode known as anamorphosis, in which new body segments are added with each molt. Although it has been known that new segments are formed between the terminal segment (telson) and the penultimate segment, the morphogenetic mechanisms underlying the formation of these new segments have remained unclear.
In this study, the researchers defined pre-molting stages based on behavioral observations and examined internal structures at each stage using X-ray micro-computed tomography (micro-CT) and other microscopic techniques. They discovered that, prior to molting, the epidermis between the telson and the penultimate segment rapidly invaginates, giving rise to a segment primordium. Furthermore, the study suggests that the insertion of a new body segment is accompanied by the rearrangement of muscles that link adjacent segments.
This research provides a foundational framework for studying the mechanisms of segment addition during anamorphosis by elucidating the dynamic tissue-level changes associated with new segment formation. Future investigations into the physiological and developmental mechanisms underlying this phenomenon are expected to expand our understanding of arthropod segmentation beyond embryonic development to the entire life history. Moreover, these insights may shed light on the evolutionary transition from ancestrally anamorphic development to the non-anamorphic developmental modes observed in insects and other arthropods.
Figure：Morphogenetic processes accompanying segment addition in juvenile millipedes, Niponia nodulosa
Links
Misaki Marine Biological Station, Graduate School of Science, The University of Tokyo,
Kobe University
Journals
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Journal name Developmental Biology AdvancesTitle of paper