Nuclear structure and chromosomal individuality. Somatic and germ nuclei of the rat

Abstract

1. Reconstruction of daughter nuclei in both somatic and germ cells of the rat is by the formation of chromosomal vesicles. The vesicles become contiguous and round off to form the spherical resting nucleus, but there is no fusion of vesicles, as evidenced by the persistence of the linin sheaths of the chromosomes. 2. The linin sheaths of the chromosomal vesicles can be seen in all resting nuclei of the rat, except in rapidly dividing cells that contain sufficient chromatin to obscure them. 3. These same sheaths can be traced well into the prophase, persisting even after the chromosomes are fully formed. 4. It is indicated that reconstruction of daughter nuclei by vesiculation or alveolization of contiguous chromosomes may be of much wider occurrence than has heretofore been thought. 5. Both plasmasome and chromatin nucleolus have the same origin. They arise from the chromosomes in the telophase. Achromatization of the chromatin nucleolus leaves the plasmasome as a residue. 6. The reticulum of each vesicle forms a unit. It is considered to be a single substance. 7. This account constitutes an extension of the direct evidence for genetic chromosomal continuity and is in agreement with the previous work on the bean and frog.