La struttura microscopica del nucleo durante il riposo

Summary

The author describes the consecutive steps in the investigation of the resting nucleus, and distinguishes a first approach using embedding and microtome technique, a second stage based on the preparation of smearings or squashes, and, thirdly, the isolation of chromatic threads (isolated chromosomes). The squash or smearing method reveals a number of different structures in different cell types and systematic species.

The question of the reliability of these structures is discussed with the following conclusions: no general model of the resting nucleus is available at the present time. In the material studied up to now with the technique of the chromosome isolation, the smeared nuclei seem to show structures which are useful for many purposes but not identical with the living structures, which are probably more closely related to the isolated chromosomes.

The isolated chromosomes, as compared with the mitotic ones, can provide new information on the spiralisation cycle, and on the length of the threads during the stage of genic activity.