Viruses and annulate lamellae in Friend erythroleukemia cells

Virus formation in a clone of murine undifferentiated Friend erythroleukemia cells was examined by electron microscopy. Budding C-type particles were present at the cell surface. The principal site of intracisternal particle production was in elements of rough-surfaced endoplasmic reticulum disposed about the periphery of stacks of annulate lamellae. Serial sections demonstrated that these virus-laden cisternae were in direct continuity with the annulate lamellae. In addition, intracisternal particles occurred in membranous honeycomb structures present in the cytoplasm of many cells. Viral elaboration also was associated with stacks of cisternae of endoplasmic reticulum that were devoid of ribosomes, but that were coated with an extensive and continuous layer of dense material. In some instances, the outer nuclear membrane was coated with the same dense substance. It appears that in Friend erythroleukemia cells, a very substantial portion of their cytomembranes is devoted to synthesis of intracisternal particles.