Three-dimensional reconstruction of mushroom body neuropils in the polychaete species Nereis diversicolor and Harmothoe areolata (Phyllodoeida, Annelida)

摘要

Mushroom bodies are prominent brain neuropils present in most arthropod representatives. Similar structures in the brain of certain polychaete species are possibly homologous to these structures. Using three-dimensional reconstruction techniques, we investigated the structural composition of the mushroom body neuropils in the polychaete species Nereis diversicolor and Harmothoe areolata. Comparative analysis revealed a common organization of neuropil substructures in both species that closely matchesthe basic assembly of arthropod mushroom bodies. Concurring with earlier homology assessments, these neu-roarchitectural similarities provide support for a common origin of mushroom body neuropils in polychaetes and arthropods. Beybnd that, differencesin the morphological differentiation of neuropil substructures indicate polychaete mushroom bodies to show a high degree of morphological variability, thus impeding the quest for a common ground pattern of these brain centers.