Islet ultrastructure: past achievements and future directions – published online 09/07/2026

Andreas Müller, Solange Aurrecoechea Duran, Patrícia I. Santos, Aubrey Weigel, Isabel Espinosa-Medina, Michele Solimena

Ultrastructure imaging has been central to our understanding of pancreatic islet biology since the earliest electron microscopy studies revealed the distinct morphology of islet cell types and elucidated the subcellular machinery of hormone secretion. In this issue, Müller et al (https://doi.org/10.1007/s00125-026-06782-7) summarise the evolution of islet ultrastructure imaging from these foundational discoveries to the development of three-dimensional imaging approaches and correlative light and electron microscopy, which enabled the visualisation of dynamic cellular processes in their structural context. The authors further describe how the increased accessibility of sophisticated imaging and analytical tools has accelerated structural investigations of islet biology across multiple scales. They also discuss unresolved questions in the field and propose the integration of complementary imaging modalities as an important strategy for linking cellular structure with islet function and dysfunction in diabetes. The figures in this review are available as a downloadable slideset.

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