ABSTRACT
To present additional data on high endothelial venule [HEV] structure and immunophenotype. We used the zinc iodide-osmium tetroxide technique [ZIO], which is a metallophilic fixation and staining technique to examine HEVs at light and electron microscopic levels as this technique was previously reported to be reactive with cells in HEVs. Tonsils and lymph nodes were obtained from the Surgery and Otorhinolaryngology Departments, Hacettepe University Hospital, Ankara, Turkey during 2002 and 2003. An indirect immunohistochemical technique was used to examine frozen human tissue samples. Organelle rich high endothelial cells, sheet-like processes of pericytes surrounding HEVs, structural relation of pericyte processes with fibroblastic reticular cells, an unusual multivesicular body-like organelle within high endothelial cells were presented. Expression of a large panel of defined and yet non-defined antigens on HEVs are also presented using an indirect immunoperoxidase technique. Presence of some of these antigens on HEVs was previously reported while no previous report is available for others. Significance of the expression of these antigens in HEVs, structural hints for trans endothelial migration of lymphocytes and their travel along the reticular cell meshwork is briefly discussed