Morphological studies of Gross virus-induced lymphoblasts by scanning electron microscopy

The surface of Gross virus-induced murine lymphoblasts and C-type virus particles budding from these cells were investigated under the scanning electron microscope (SEM). The cells appeared spindle-shaped or roughly-rounded with extensive surface features consisting of microvilli, blebs and ruffled membranes. C-type virus particles were detected on the cell membrane as small spherical particles, distinguishable from the microvilli. Clustered virions were observed in some cases. However, the distribution of virions appeared to be random. The surface of the virion was smooth and had no globular units at high magnification. These morphological observations were confirmed in ultrathin sections.</p

Electron microscopic study on the surfaces of Gross virus-induced murine leukemia cells and budding virions

A study was made on alterations in the surface structures of Gross virus-induced murine thymic leukemia cells and budding virions with freeze-etching technique. The budding virions were clearly observed on the fractured faces of cell surface as well as microvilli and ruffled membranes. Knobs, approximately 10 nm in diameter, were demonstrated on the surfaces of budding virions. Extracellular virions had also the similar structure on their surfaces. On the fractured protoplasmic face (P.F.), 8.5-10 nm typical intramembranous particles (I.P.) were arranged randomly without detectable aggregated particles. There also appeared smooth semispherical protrusions which could be regarded as budding virions. Comparison was carried out between numbers of I.P. in leukemia cells and those in normal thymocytes, showing that I.P. slightly increased in leukemia cells