| Comments |
P.303 bottom paragraph to p.306 top paragraph:"Incidence and duration of apoptosis. Because cells usually undergo apoptosis individually and remain surrounded by intact cells in tumour sections, they are easily overlooked and in general apoptosis is a poorly-quantified phenomenon. However, as shown in Table 12.2 untreated tumours in animals and man may contain a proportion of ‘apoptotic’ cells that is comparable to, or greater than, the commonly-measured mitotic cells. The probability of encountering a given feature in a histological section is the result of its relative incidence in the population and its duration as a recognizable entity. Mitosis typically occupies half to a few hours in animal and human tumours (e.g. Iversen 1967). The duration of apoptosis is less well characterized. As emphasized most recently by Wyllie (1985), the initial phase of cell degradation may occupy only minutes and it is the subsequent degradative phase within phagocytic vacuoles of tumour macrophages or other tumour cells (e.g. Kerr et al. 1972 Youness et al. 1980) that has a half-time of hours. Weinberger and Banfield (1965) noted that only 1 in 300 ‘necrobiotic’ cells in a reticulum cell sarcoma was not in the vacuoles of macrophages." |