The appearance of cluster forming cells in cultures correlates with activation of astrogliosis within the spinal cord.

<p>(A, B and C) Micrographs demonstrate overlay of GFAP positive cells and nestin in sections obtained through the center of MMC lesion at E19, E20, and E21. A small population of astrocytes was identified only in the exposed dorsal area of spinal cord in MMC fetuses at E19, the intensity of GFAP staining and density of reactive astrocytes expressing nestin increased at E20, and a marked astrocytosis characterized by the presence of nestin expressing astrocytes was found throughout the exposed spinal cord tissue in MMC fetuses at E21. (Magnification 10 X). (D, E and F) Representative micrographs of MMC-AF cells 24 hour after plating demonstrate GFAP positive cells and nestin positive cells in cultures from E19, E20 and E21. (D) Double immunofluorescence staining for the expression of GFAP and Nestin shows scattered GFAP positive cells and/or nestin positive cells, which rarely co-expressed these two markers in cultures from E19. Arrowhead denotes a cell double-positive for GFAP and nestin. (E and F) Double immunofluorescence staining for the expression of GFAP and Nestin shows adherent clusters of multilayered cells containing many GFAP and nestin double positive cells in cultures from E20 and E21. (Magnification 20 X).