Subchromatid structure of chromosomes in the living state

Abstract

Using endosperm of Haemanthus katherinae as a material and the 16 mm time-lapse micrographic technique, it has been found that chromosomes show half-chromatid structure clearly in mid-anaphase and telophase, and sometimes in prometaphase-metaphase. During the chromosome cycle in one cell, such structure appears clearest at certain stages, sometimes only for a very short period of the chromosome cycle. Visibility depends to a great extent on the degree of chromosomal coiling. When the half-chromatids are coiled around each several times, visibility is obscured and when half-chromatids are more or less parallel, visibility is much better. Additional data concerning half-chromatid structure during chromosome and kinetochore stretching and chromosome bridges have been supplied. Also conditions on which visibility depend have been briefly discussed.