Figure 4.

Sinus and nonsinus AG types are observed on postmortem examination. (A) A schematic depicts frontal levels studied on expanded frontal convexity sampling (left), and variable AG dome positions identified (right). (B) Intermediate-power image of the frontal perisinus region demonstrates epidural type (i.e., Type IV) AG, in this case with partial trilaminar ensheathment. H&E-stained section shows well-defined meningothelial AG capsule with partial ensheathment by dural connective tissue and DVS enthothelium, as confirmed by immunoperoxidase labels for vimentin, epithelial membrane antigen (EMA), and CD31. A cropped image of the granulation edge, shown on the lower right-hand side, depicts the trilaminar capsular investments. (C) Another image demonstrates stromal type (i.e., Type II) AG, with dome embedment within DAS. (D–F) Enlargements of cropped AG images in longitudinal (D) and cross section (E and F) orientation are shown. The enlarged images depict DAS envelopment of the apical AG dome region and communication of the AG core with the subcapsular space and DAS (gray arrows). (G) AG types present along frontal convexities are summarized. (H) AG types present at distinct frontal levels are summarized. (I) MHCII-expressing APC and CD4-expressing T cells are depicted in sinuses and crypts of a Type II AG, with multifocal label overlap suggesting the presence of immune synapses (inset). (J and K) Results of select immune cell, cytokine, chemokine and other labels are summarized according to age (J) and AG type (K). (L and M) The percent overlap of MHCII (APC) and CD4 (T cell) label, suggestive of immune synapses, is summarized at frontal levels (L) and in distinct AG types (M). (I) Green/FITC, MHCII; violet/CY3, CD4; cyan/CY5, CD11c. Scale bars: (B–D) 200 µm; (E) 100 µm; (F and I) 50 µm. Histological features depicted are from a middle-aged adult. Data summarize findings in 124 granulations from frontal convexities of 15 decedents and are from more than two independent experiments.