STRUCTURAL CHARACTERIZATION OF NEOVASCULARIZATION IN ADENOVIRUS‐12‐INDUCED RETINAL TUMOR

In order to elucidate a relationship between newly formed micro‐blood vessels in retinal tumor and blood‐retina barrier, we studied light and electron microscopic and immunohistochemical findings of newly‐formed micro‐blood vessels in human adenovirus 12‐induced retlnoblastoma‐Hke tumors in rats. In contrast to other experimentally induced tumors of the central nervous system, there was no evidence of formation of Weibel‐Palade bodies and endothelial gaps in this experimental model of retinoblastoma, but factor VIII related antigen was evidently demonstrated. Increased pinocytotic vesicles suggested that the vast majority of these blood vessels did not retain the normal physiological barrier functions. The basement membrane of the micro‐blood vessels was poorly developed. The morphological characteristics of the micro‐blood vessels of this retinoblastoma‐like tumor were compared with those of human retinoblastoma and other experimentally induced tumors of the central nervous system.