Section of 5-day-old C6/36 cell cultures infected with CsFV. (A) Spherical virus particles associated with cisternae of the endoplasmic reticulum. N, cell nucleus. Magnification, 31,000 ×. (B) Dense accumulations of mature virus particles associated with distended cisternae of endoplasmic reticulum and intercisternal tubular membranes. Magnification 48,000 ×. (Inset) Higher magnification of mature enveloped virions. Magnfication, 155,000 ×.