Fine structure, functional organization and supportive role of neuroglia in Nereis.

Fluorescence and electron microscopy reveal a dynamic architectural pattern in the organization of neuroglia in the central nervous system of nereid polychaetes. Fibrous glial processes intertwine among neuronal elements, binding them together, and anchor the nerve cord to the epidermis. Rigidity and resilience are provided to this supportive framework by glial filaments and desmosomes. Tensive stresses, arising from contraction of locomotory muscles attached to the nerve cord, may be dissipated over the web-like meshwork, thus reducing the potential influence of deformative forces on neuronal elements within the neuropile. The voluminous glial processes forming the peripheral zone of the nerve cord may protect neurons from compressive forces.