The skin of three cases of generalized morphea in the active stage was studied by electron microscopy. The following cells were identified within areas of panniculitis: plasma cells, macrophages, and lymphocytes. Fibroblasts revealed a well developed rough endoplasmic reticulum filled with granular material. Phagocytosis of fat by macrophages was a prominent feature. Fat trabeculae were increased in thickness due to the deposition of immature collagen fibrils, ranging in diameter from 200 to 400 Angstroms. Collagen fibrils alternating in their orientation at a 90° angle were present in the lower dermis and in the subcutaneous tissue. A bimodal distribution of collagen fibrils was noted and consisted of fibrils of 350 and 950 A in diameter.
Fleischmajer R, Prunieras M. II. Electron Microscopy of Collagen, Cells, and the Subcutaneous Tissue. Arch Dermatol. 1972;106(4):515-524. doi:10.1001/archderm.1972.01620130047011