FIG 3. Histologic and immunohistochemical features of the swine AVM models.

A, Immunohistochemical features of the nidus microvessels in the acute AVM model (ie, of normal rete mirabile microvessels) using monoclonal antibody to smooth muscle actin, followed by counterstaining with hematoxylin-eosin. Original magnification x40.

B, Histologic section of the 2-month-old nidus vessels after staining with elastica van Gieson. Note the prominent intimal hyperplasia that occludes vessels in places and prominent disruption of the elastica. Original magnification x16.

C, Immunohistochemical features of the nidus microvessels in the 2-month-old AVM model using monoclonal antibody to smooth muscle actin, followed by counterstaining with hematoxylin-eosin. Note medial thickening and intimal hyperplasia. Original magnification x40.

D, Immunohistochemical features of the nidus microvessels in the 2-month-old AVM model using PC10 antibody to PCNA followed by counterstaining with hematoxylin-eosin. Note widespread presence of proliferating cells. Original magnification x104.

E, Histologic section of the 2-month-old nidus vessels after staining with mucicarmine. Note the mucicarmine-positive ground substance among cells of hyperplastic intima. Original magnification x40.

F, Histologic section of the 6-month-old nidus vessels after staining with elastica van Gieson. Note the multifocal destruction of the elastica layer (arrow) and the intimal hyperplasia in the form of an endoluminal cushion (arrowhead). Original magnification x40.

G, Histologic section of the 6-month-old nidus vessels after staining with hematoxylin-eosin. Note the focal segments of mural thinning (arrow). Original magnification x40.