Figure 1: Light micrographs (LM) and transmission electron micrographs (TEM) of the same cellular elements but different sections present the internal limiting membrane (ILM) (asterisk) removed from eyes with diabetic macular edema, stage IV idiopathic macular hole, and proliferative vitreoretinopathy (from top to bottom). The ILM is characterized by an undulated retinal side and a smooth vitreal side. (A, B) Cell membrane fragments (arrow) on the retinal side of the ILM. The vitreal side of the ILM (arrowhead) is devoid of cells and collagen. (Specimen removed for diabetic macular edema, original magnification: LM 40x; TEM x9,500; scale bar = 1.0 μm). (C, D) Light micrograph shows a cell with nucleus on the retinal side of the ILM, EM shows one large cell fragment (arrow) in contact with ILM (asterisk), and a single cell on the vitreal side of the ILM (arrowhead) which shares features with fibrous astrocytes such as masses of intermediate type filaments, rough endoplasmic reticulum and electrondense particles. (Specimen removed for stage IV idiopathic macular hole, original magnification: LM 100x; TEM x4,800; scale bar = 2.0 μm). (D, E) Entire cell body with cellular nucleus (arrow) located on the retinal side of the ILM (asterisk). The vitreal side of the ILM (arrowhead) is blank. (Specimen removed for proliferative vitreoretinopathy, original magnification: LM 100x; TEM x9,500; scale bar = 1.0 μm).