Ultrastructure of cultured human orbital fibroblasts.

The fine structure of cultured human orbital fibroblasts was investigated by transmission electron microscopy. One culture was derived from a patient with severe Graves' ophthalmopathy, the other from a donor without inflammatory orbital disease. Despite their known differences in metabolism, orbital fibroblasts from either source revealed no ultrastructural differences. The cells had extensive thin cytoplasmic processes. The perinuclear areas contained multiple assemblies of Golgi membranes, modest amounts of rough endoplasmic reticulum, intermediate filaments, and lysosome-like structures. Glycogen deposits were noted both in the perinuclear cytoplasm and in the thin processes. These ultrastructural features of orbital fibroblasts are the same as those of fibroblasts from other anatomic regions.