Syncytial nerve net in a ctenophore adds insights on the evolution of nervous systems

Science. 2023 Apr 21;380(6642):293-297. doi: 10.1126/science.ade5645. Epub 2023 Apr 20.

Abstract

A fundamental breakthrough in neurobiology has been the formulation of the neuron doctrine by Santiago Ramón y Cajal, which stated that the nervous system is composed of discrete cells. Electron microscopy later confirmed the doctrine and allowed the identification of synaptic connections. In this work, we used volume electron microscopy and three-dimensional reconstructions to characterize the nerve net of a ctenophore, a marine invertebrate that belongs to one of the earliest-branching animal lineages. We found that neurons in the subepithelial nerve net have a continuous plasma membrane that forms a syncytium. Our findings suggest fundamental differences of nerve net architectures between ctenophores and cnidarians or bilaterians and offer an alternative perspective on neural network organization and neurotransmission.

MeSH terms

  • Animals
  • Biological Evolution*
  • Ctenophora*
  • Nerve Net / physiology
  • Nervous System*
  • Neurons / physiology
  • Synaptic Transmission