Internal Structure of the Virus-like Particles associated with the Rous Sarcoma, and their Presence in other Neoplastic and Normal Chicken Tissues

Abstract

IN ultra-thin sections of two out of three Rous sarcomas, Gaylord¹ found virus-like particles of spherical shape with a diameter varying from 45 to 60 mµ. They were characterized by a dense central core measuring about a third to a half the diameter and by a single outer membrane. These elements were mostly either isolated or in clusters outside the cells, clinging to the surface of the cell membrane; less frequently they were found in small vesicles within the cytoplasm. These observations have recently been confirmed on a larger scale comprising fifty-four Rous sarcomas grown on young chicks and twenty-one tumours grown on the chorioallantoic membrane². In 41 cases of the first (76 per cent) and in 13 (62 per cent) of the second group, variable numbers of such particles were found, mostly extracellularly but also within the cytoplasm. Their size, however, was found to vary between 60 and 80 mµ. Further details concerning these findings and the reasons why they are believed to be the causative agent of the Rous sarcoma are discussed elsewhere².