title: Spontaneous mammary tumours in SPF C3H-A vy  mice: formation of virus structures.
mesh_terms: D000818:Animals; D005260:Female; D005856:Germ-Free Life; D008325:Mammary Neoplasms, Experimental / Q000382:microbiology* / Q000473:pathology; D008324:Mammary Tumor Virus, Mouse / Q000302:isolation & purification*; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron