The organization of astrocytes in organotypic mouse spinal cord culture: an electron microscope study.

The organization of astrocytes in myelinated culture of mouse spinal cord tissue was analysed ultrastructurally and compared with the pattern in vivo. Astrocyte cell bodies and their processes, connected by punctate adhesions and gap junctions, formed a continuous layer around the entire explant. Throughout the parenchyma, thin astrocytic processes penetrated the neuropil, separated neurons, and invested some synaptic complexes. Others formed flattened sheets and contacted directly with the basal surface of ependymal cells. In the absence of mesenchymal elements, astrocytes in vitro occasionally possessed fragments of basal lamina on the surface of the explant and around minute intercellular spaces. Except for an incomplete basal lamina, these findings indicate that astrocytes in vitro are organized in a manner essentially identical to the situation in vivo.