[Pathology of mitosis after cellular recovery from a metaphase block].

The experiments in Chinese hamster fibroblast-like cells have shown that the c-mitosis inducing agents (colchicine, colcemid and low temperature) produce evident stathmokinetic and radiomimetic effects. By the reversibility moment of the former the latter becomes apparent, manifesting in bridge accumulation. This form of pathology is likely to be caused by the disturbance of the cellular nucleoprotein metabolism in c-mitosis.

[Characteristics of mitosis pathology in a Chinese hamster cell culture with disorders of the protein-synthesizing system].

Disturbance of protein synthesis with puromycin and transcription of chromosomal and ribosomal RNA with actinomycin D was followed by marked changes in the normal course of mitosis. There was noted an increase in number of colchicin-like mitoses (C-mitoses), and particularly, sometimes, fragmentation of their cytoplasm with the formation of cluster-like structures. It is suggested that development of C-mitosis was connected not only with destruction in the mitotic apparatus formation system, but also with the block of synthesis of one of the chromosomal proteins, stabilizing DNA strands spiralization.

[Remote changes in the course of mitosis in synchronized cultures of Chinese hamster cells following inhibition of RNA and protein synthesis].

The effect of inhibition of the synthesis of some types of RNA and proteins was determined in the synchronized culture of Chinese hamster cells at various stages of the interphase on the course of remote mitosis. Analysis of MI and some forms of pathological cell division showed that the action of different doses of AMD and pyromycin during the first part of the interphase provoked an identical effect--C-mitosis at the immediate and remote waves of cell division. Suppression of the synthesis of whole cell RNA and proteins during the second half of the interphase was accompanied by a metaphase cell delay with scattering chromosomes, this indicating derangement of the synthesis of the division spindle component.

[Mechanism of reversibility of colchicine mitosis induced by colcemid].

Restoration of the normal mitosis after its block by colchicine was due to the additional protein synthesis (reformation of the spindle microtubules). Studies of reversibility of the statmokinetic reaction induced by colcemid showed the block of the protein synthesis by puromycin to have no influence on the rate of restoration of the normal mitotic regimen, but copper ions delayed this process. On the basis of these results it is considered that restoration of the K-mitosis induced by colcemid was mainly due to the tubule reassembly.

Experimental study of the functional morphology of the kinetochore in mitosis.

Chinese hamster cells in culture were blocked in prometaphase by the addition of chloral hydrate. After 2 h the chloral hydrate was removed and the ultrastructural changes in the kinetochore studied during recovery of mitosis. The kinetochore in the blocked cells is a disc measuring 300-350 nm in diameter and 30-35 nm in thickness.

[Morphologic and applied aspects of mitotic pathology].

The author presents a classification and descriptions of various forms of pathology of mitosis. Changes in the mitotic regimen following administration of some drugs and under the effect of extreme factors are considered. Data on changes in the number and character of pathological mitoses in viral infection and radiation damage are discussed.