Fig. 3 in Loss of complexity from larval towards adult nervous systems in Chaetopteridae (Chaetopteriformia, Annelida) unveils evolutionary patterns in Annelida

Fig. 3 Adult histology, details of brain and sensory structures, sections of anterior body region A (according to chaetopterid nomenclature). a, c, d: Spiochaetopterus costarum; b: Chaetopterus norvegicus. a: the brain (br) is composed of densely interwoven neurites (ne). Somata (so) are located dorsally of the neurites (ne). Intermediate filaments (if) are attached to the basal lamina (bl) and cross the neuropil. b: In between the neuropil of the brain nuclei of glial cells (nugc) can be found. Neurites (ne) are of different diameter. bl: basal