Specialized postcapillary venules in human gingival tissue.

High endothelial venules (HEV) are specialized postcapillary venules that play a central role in lymphocyte migration and recirculation. This study examined the occurrence and morphology of HEV-like vessels in healthy gingiva and in lesions of chronic gingivitis in children, experimental gingivitis in adults, adult periodontitis, and in periapical granulomas. HEV-like vessels were absent in gingival health, but present during the development of inflammation and in chronic inflammation. The morphology of these HEV-like vessels in the oral cavity resembled that of lymphoid HEV. Thus gingival HEV may represent sites for the entry of lymphocytes into chronic inflammatory lesions.