Ultrastructural images of a unilobed AG depict its surface and internal morphology. (A) Toluidine blue–stained thin section of a unilobed AG displays the AG stalk and body in longitudinal orientation. (B–D) Ultrastructural images of different surface (boxed) regions demonstrate areas of intact (B), partial (C), or no (D) capsular coverage. Note areas of communication between the AG core and periapical region (yellow arrows in C and D). (E) The internal core stroma depicts trabeculae that are unlined (left arrow) or lined (right arrow) by fibroblast-like cells, consistent with meningothelium. High-power micrograph image of the blue boxed area is shown in the inset at right and demonstrates a trabeculum comprised of densely packed collagen fibrils. (F) A toluidine blue–stained thin section of a different granulation from the same decedent is shown in axial orientation, along with micrographs of the boxed areas. Note sinuses on the left and larger, gaping crypt spaces on the right-hand side. Both the sinus and crypt spaces contain cell debris and rounded mononuclear cells at their margins. (G) Enlarged images of sinus and crypt spaces show diverse cell types. (H) On an immuno-EM image prepared using a primary antibody directed toward CD68, many rounded stromal cells are confirmed as macrophages; see insets (i.e., enlargements of red boxed areas) at right-hand side that depict cytoplasmic and lysosomal electron-dense label. (A and F [inset]) Toluidine blue–stained thin sections; (B–G) TEM; (H) immuno-electron micrograph. Scale bars: (B, C, and E [left]) 2 µm; (D and H [middle]) 500 nm; (E [right] and H [right]) 200 nm; (F and H [left]) 5 µm; (G) 1 µm. Single blue asterisk (*) represents a sinus space. Double blue asterisks (**) represent a crypt space. Features shown are from a middle-aged adult. Data summarize findings in >30 granulations from frontal pole AG of three decedents and are from more than two independent experiments.