Department of Integrative Biology

We describe a group of neurons with egg-laying bioactivity in the cerebral ganglia of an opisthobranch mollusc, the nudibranch Archidoris montereyensis. These cells, the intercerebral white cells (IWCs), share morphological, biochemical, and electrophysiological characteristics with the egg-laying neuroendocrine cells of two other molluscs, Aplysia californica (bag cells) and Lymnaea stagnalis (caudodorsal cells). The IWCs, comprising two superficial clusters of about 100 neurons each, were located immediately posterior to the intercerebral commissure in the cerebral ganglia. The somata of these cells were small (