Whole-animal connectome and cell-type complement of the three-segmented Platynereis dumerilii larva
Csaba VerasztóiD, Sanja JasekiD, Martin GühmanniD, Réza ShahidiiD, Nobuo UedaiD, James David Beard, Sara Mendes, Konrad J. Heinz, Luis Alberto Bezares-CalderóniD, Elizabeth A. WilliamsiD, Gáspár JékelyiD
Abstract
Nervous systems coordinate effectors across the body during movements. We know little about the cellular-level structure of synaptic circuits for such body-wide control. Here we describe the whole-body synaptic connectome and cell-type complement of a three-segmented larva of the marine annelid Platynereis dumerilii. We reconstructed and annotated over 1,500 neurons and 6,500 non-neuronal cells in a whole-body serial electron microscopy dataset. The differentiated cells fall into 180 neuronal and 90 non-neuronal cell types. We analyse the modular network architecture of the entire nervous system and describe polysynaptic pathways from 428 sensory neurons to four effector systems - ciliated cells, glands, pigment cells and muscles. The complete somatic musculature and its innervation will be described in a companion paper. We also investigated intersegmental differences in cell-type complement, descending and ascending pathways, and mechanosensory and peptidergic circuits. Our work provides the basis for understanding whole-body coordination in annelids.
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Abstract summary
Claude Opus 5.5 · xhigh effort · 18 Oct 2026 · from the abstract · CC BY-ND 4.0
A whole-body serial electron microscopy volume of a three-segment Platynereis dumerilii larva gives over 1,500 reconstructed neurons, 6,500 non-neuronal cells, 180 neuronal types and traced sensory-to-effector pathways.
Coordinating movement across a whole body needs circuits that span the whole animal, yet cellular-resolution wiring diagrams at that scale are scarce. Here the whole body of one larva is reconstructed at synaptic resolution, so pathways from sensory neurons to ciliated cells, glands, pigment cells and muscles can be followed within one specimen.
Key results
ShownA whole-body synaptic wiring diagram and cell-type catalogue for the three-segmented larva: more than 1,500 neurons and 6,500 non-neuronal cells reconstructed and annotated, with differentiated cells assigned to 180 neuronal and 90 non-neuronal types.
Counts reported directly from the whole-body serial electron microscopy reconstruction; no agreement, proofreading or completeness statistics are given. · Abstract
SuggestedRoutes of several synapses are traced from the larva's 428 sensory neurons out to four kinds of effector - ciliary cells, pigment cells, glands and musculature - and the nervous system as a whole is described as modular.
Pathway tracing over the reconstructed connectome with 428 sensory neurons as starting points; the abstract names the four effector systems but reports no modularity score, pathway lengths or synapse counts. · Abstract
ClaimedFurther analyses of segment-to-segment differences in cell-type complement, of descending and ascending pathways, and of mechanosensory and peptidergic circuits are reported, but the abstract does not state what these showed.
Listed as topics the authors investigated; no outcome, comparison or statistic for any of them appears in the abstract. · Abstract
Methods, data and reproducibility
Cells were reconstructed and annotated in a whole-body serial electron microscopy dataset of a three-segmented Platynereis dumerilii larva, then classified into neuronal and non-neuronal types and analysed for network modularity and for pathways linking sensory neurons to effector systems.
- Whole-body serial electron microscopy dataset of a three-segmented larva · Platynereis dumerilii · n = over 1,500 neurons, 6,500 non-neuronal cells, 428 sensory neurons
- Methods & tools
- serial electron microscopy
Limitations (2)
- The full somatic musculature and how it is innervated are left to a companion paper, so the muscle effector arm of the circuit is not completely covered here. · stated by the authors
- The wiring diagram comes from a single larva at one developmental stage, so variation between individuals or across stages cannot be judged from it. · noted in this summary
Who should read:Read this if you work on connectomics, invertebrate neuronal cell-type catalogues, or circuit-level accounts of whole-body sensory-to-effector coordination.
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