Development of glial cytoarchitecture in the frog spinal cord

The origin of astrocytes and oligodendrocytes in the frog spinal cord, and the factors that regulate their differentiation are currently unknown. To determine the timing and pattern of glial cell differentiation, spinal cord sections from Xenopus at different developmental stages were labeled with antibodies specific for astrocytes and oligodendrocytes. Initially, radially oriented glial cells are present in all spinal cord quadrants and their processes contain similar levels of GFAP+ intermediate filaments in both gray and white matter. These cells then appear to differentiate directly into regionally specialized radially oriented astrocytes. Oligodendrocytes labeled with the 'Olig' antibody, however, are first detectable in the ventral quadrant. Differentiation subsequently occurs in a ventral-to-dorsal sequence beginning at the interface between the gray and white matte. These data suggest that the origin and regulation of Xenopus astrocyte and oligodendrocyte differentiation are distinct.