Specialized contacts of astrocytes with astrocytes and with other cell types in the spinal cord of the cat

Adult and half grown healthy male and female cats were used in this study. The white and gray matter of dorsolateral region in the upper lumbar levels of the spinal cord were examined by electron microscopy after fixation by aldehyde perfusion and commonly used methods of embedding, sectioning and staining. The report is limited to description and illustration of specialized junctions of astrocytes. In addition to previously described astrocyte-astrocyte gap junctions, astrocytes are connected by gap junctions to oligodendroglia cells and to neurons. Astrocytes also are connected with each other and with neurons by juctions characterized by wide (250 A) gaps containing opaque gap material and by dense material adhering to the inner surfaces of the plasma membranes. The results suggest a morphological basis for adhesion and intercommunication between all adult derivatives of the embryonic neural tube.