Electron microscope study of glial and fibroblast hybrid cells

The ultrastructure of a clone of rat glial cells, 3T3 mouse fibroblasts, and hybrids of these two cell types was compared. In the hybrids, morphological characteristics of glial cell are poorly expressed, whereas those of fibroblasts are strongly expressed. Microfibrils are seen in both parental lines. Microtubules and osmiophilic inclusions, which are frequently found in glial cells and are absent in fibroblasts, are quite rare in hybrids. By contrast, highly reticulated nucleoli, typical of fibroblasts, are prolific in hybrids. The lack of morphological expression of glial characteristics in hybrids is consistent with previous biochemical data on the expression of different functions in hybrids.