Different cell populations in retinoblastoma

By evaluating the nuclear contours of cell populations in 35 cases of retinoblastoma in routine hematoxylin and eosin stained sections and drawing them on microphotographic material, we determined an intermediate differentiated cell population among rosette tumors and undifferentiated tumors and noted the presence of trabeculoid grouping of the cells and the existence of nuclear shaping. There is a predominance of well differentiated and intermediately differentiated tumors intraocularly, and of poorly differentiated cell populations in extraocularly invaded areas.