Portal de Periódicos da CAPES

Somatic Mutations as a Factor in the Production of Cancer: A Critical Review of v. Hansemann's Theory of Anaplasia in the Light of Modern Knowledge of Genetics

1919; American Association for Cancer Research; Volume: 4; Issue: 2 Linguagem: Inglês

10.1158/jcr.1919.181

0099-7013

R. C. Whitman,

Nutrition, Genetics, and Disease

For nearly thirty years the phenomenon known by von Hansemann9s term, anaplasia, has been widely used among pathologists to describe and explain the origin of cancer cells. Any well established facts, therefore, which throw added light upon the nature of the process of anaplasia itself and any possible relation it may have to cancer genesis must be important and significant. The term anaplasia has been, however, so loosely used that it will be worth while to review at length von Hansemann9s theory in order that we may start with a clear conception of what the word really means. The pleomorphism of cancer cells and the irregular, atypical mitoses so characteristic of their nuclei had been observed and carefully studied since the middle of the nineteenth century. Arnold (Virch. Arch., vol. 79, cited by von Hansemann (1)), observing irregularities in the mitotic process itself, had inferred that these might be of fundamental significance. A voluminous literature dealing with the mitoses in cancer cells and other forms of rapidly proliferating tissues had already accumulated when von Hansemann (1) undertook a further investigation in the same field. In a carcinoma of the larynx he found besides a great abundance of normal mitotic figures, large numbers of tripolar and multipolar divisions and other departures from the normal type already observed and described by earlier writers; and in addition many hyperchromatic and hypochromatic mitoses, the hypochromatism consisting not merely in a reduction of the amount of chromatin in the chromosomes but rather in an actual reduction of the total number of the chromosomes. He reproduces a monaster with only nine chromosomes. Further search led to the finding of a hypochromatic diaster one member of which contained five chromosomes, the other eight, or possibly nine. This asymmetry of division, which he regarded as analogous to the process by which he believes that differentiation, or specialization of the cells occurs during normal embryonic development, might, he thought, take place either as the result of delay, or of complete failure of the chromosomes to split longitudinally during the mitotic process; or else through failure of the two longitudinal halves of the chromosomes to separate and pass to the opposite ends of the spindle. In one of his cases he found numerous instances in which, in the monaster stage, late in the metaphase, (or telophase), the chromosomes were found lying in pairs close to and parallel with one another, indicating that splitting had occurred shortly before. Since splitting normally occurs early in the anaphase, he inclines to the view that the asymmetry in question is due to delayed splitting, at least in some instances.