Light (A, B) and transmission electron (C) micrographs showing AEFC. (A) Principal fibers (PF) enter AEFC (*) as extrinsic fibers. D, dentin. Hematoxylin and eosin-stained paraffin section. Bar 50 μm. (B) Extrinsic fibers are observed as white lines in AEFC. Extrinsic fibers change their orientation at the intensely stainable incremental lines (arrows). D, dentin. Hematoxylin-stained ground section. Bar 50 μm. (C) Extrinsic fibers are branching and anastomosing. D, dentin; CB, cementoblasts; PC, precementum; PF, principal fibers. Bar 5 μm.