III. A Cytological and Cytochemical Approach to an Understanding of Radiation Damage in Dividing Cells

Abstract

Cells of Trillium erectum were treated with 50 r of X-rays at various stages of microsporogenesis and chromosome fragmentation was scored at 2 subsequent stages. Sensitivity to chromosome breakage increases during meiotic prophase to a peak near diplotene and then decreases to a low point in early interphase. During the period of increasing sensitivity there is an increase in desoxypentose nucleic acid (DNA); but decreasing sensitivity occurs while DNA remains constant. Neither the content of DNA nor of pentose nucleic acid is directly related to radiosensitivity.