Viral Apoptosis.Coloured scanning electron micrograph (SEM) of a cultured cancer cell which has become apoptotic after infection with the HIV virus. In addition to inducing immune and inflammatory responses, infection by most viruses triggers apoptosis or programmed cell death of the infected cell. This cell response often results as a compulsory or unavoidable by-product of the action of critical viral replicative functions. Characteristics of apoptosis at SEM level are membrane blebs called apoptotic bodies. In culture, apoptotic cells typically undergo further degradation in a process called secondary necrosis seen here as multiple holes in the cell membrane. Magnification: x8000 when printed at 10 centimetres wide. Specimen courtesy of Greg Towers, UCL.