Beyond the beginning – development that lasts a lifetime

[Editorial from Development’s latest Special Issue – Lifelong Development: the Maintenance, Regeneration and Plasticity of Tissues, edited by Merixtell Huch and Mansi Srivastava.]

Traditionally, developmental biology has been considered the study of the embryo, and significant events such as metamorphosis or birth signify the pinnacle of development. However, we now better appreciate that development is a continuum and that – as in plants – developmental processes occur throughout the lifetime of an animal. Cell fate specification and differentiation, morphogenesis and patterning can continue after embryonic development; growth, degrowth, ageing, regeneration, and even reverse development (e.g. in some disease states) are just some examples of development-like processes occurring during the life history of a species. This special issue sought to draw these connections and to highlight how embryonic studies have revealed fundamental lifelong principles, advocating for a broader interpretation of developmental biology that circumvents restriction to specific stages in the life cycle.

The 26 research and review-type papers published in this issue illustrate this goal, including a breadth of mechanisms, research organisms and organ types. A selection of Research Articles demonstrates how several tissues and organs continue to develop, differentiate and mature during post-embryonic stages, establishing the principle of lifelong development. These examples include the mouse gut (Pan et al., 2025) and adipose tissue (Mahapatra et al., 2025), zebrafish vasculature (Preußner et al., 2025), and the Caenorhabditis elegans germline (Gupta et al., 2025). The mammalian nervous system represents a particularly well-studied example of postnatal refinement in response to sensory stimuli and learning. Therefore, we are glad to capture studies that discuss the ongoing development of retinal cells (Shah et al., 2025) and visual cortex (Xavier et al., 2025), microglia (Hammond et al., 2025), astrocytes (Iyer et al., 2025) and neurons (Liu et al., 2025). In addition to an extension of embryonic development, some tissues and organs undergo extensive remodelling during metamorphosis in invertebrates or puberty in humans (Rauner et al., 2025), and tissue-resident stem cells are crucial for the homeostasis and maintenance of adult tissues, which may also change behaviour over a lifespan due to shifting niche environments (Puri and Blanc, 2025).

Beyond these examples of post-embryonic development, regeneration offers perhaps the most striking illustration of development-like processes occurring in adults. We are therefore excited that regenerative studies are well represented in the special issue. Research papers characterise the initial molecular events and signalling in regeneration (Quinn et al., 2025), as well as the regeneration of specific tissues and organs, such as the zebrafish skin (Craig et al., 2025) and heart (Feng et al., 2025; Forman-Rubinsky et al., 2025). Whole-body regeneration is also explored in planarians, with studies revealing how these species maintain robust regenerative potential throughout life (Zelko et al., 2025), and the mechanisms by which polarity and patterning are re-established during regeneration (Anderson and Petersen, 2025; Miliard et al., 2025). In addition, our review-type content highlights a recent workshop from this field (Bayin et al., 2025), the interplay between vertebrate regeneration and the nervous system (Wakelin and Johnston, 2025; Tendolkar and Mokalled, 2025) and non-traditional model systems with remarkable regenerative potential (García-Arrarás et al., 2025). We are pleased that one of these organisms, the tapeworm, also features in a Research Article in the same issue (Nanista et al., 2025). Moreover, our Techniques and Resources articles provide valuable references for studying adult stages of highly plastic species (Temiz et al., 2025; Little et al., 2025), with a Hypothesis article exploring such phenotypic plasticity as the basis of complex developmental potential (Dardiry and Ikmi, 2025).

This special issue underscores the continuity of developmental processes across the lifespan from embryogenesis to regeneration, tissue maintenance and phenotypic plasticity. By linking classical developmental biology and emerging insights into post-embryonic and adult stages, we aim to broaden the field’s conceptual understanding of developmental biology. We hope you enjoy reading the issue and that it inspires further investigation of how developmental mechanisms operate beyond early life, adapt to environmental cues, and contribute to lifelong organismal plasticity. Development welcomes future submissions that explore these dynamic and evolving aspects of development across diverse systems and life stages.

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