Abstract
Fine fibrillar structures could be observed in the peripheral cytoplasm of non-glycerinated mesangial cells. And similar structures were also observed in the peripheral cytoplasm of the cell body of the non-glycerinated glomerular epithelial cells, as well as at the primary processes and secondary processes which were so-called foot ones. In the glycerol treated cells, it was found that the linear thin filaments (50-70 Å in diameter) with parallel arrangement and the rod shaped thick ones (120-130 Å in diameter, 0.15 μm in mean length) parallel to each other, tapering at both sides were located similarly in the case of non-glycerinated mesangial cells. The fibrillar structures in non-glycerinated glomerular epithelial cells were found also in glycerinated ones. In a higher magnification of figures in glycerinated ones, many linear thin filaments (50-70 Å in diameter) with parallel arrangement were found at the location where the similar filaments had been detected in non-glycerinated glomerular epithelial cells, and spindle shaped thick filaments (130-200, 0.14m in mean length) oriented randomly were observed scattering in the peripheral cytoplasm of the cell body and primary processes but not in the foot processes of the epithelial cells. The thin filaments in the two kinds of cells were found to form arrow head structures (HMM-THIN FILAMENTS COMPLEX) in response to the addition of skeletal HMM, which is observable in the filaments of F-actin and those containing actin in various non-muscular cells. The morphological characteristics of rod shaped thick filaments in glycerinated mesangial cells were similar to those of filaments containing myosin from muscles, and the characteristics of spindle shaped thick ones in glycerinated glomerular epithelial cells were similar to those of filaments containing myosin from various non-muscular cells. These thin and thick filaments were thought to be correspondent to myofibrils in muscles.
