al., 1978; Ghosh, Paweletz, 1984; Stephenson, Gooday, 1984;
Petrashchuk, Onishchenko, 1987, etc.). It should be noted that their
interpretations are not unidirectional and in most cases they are considered
as unusual phenomena or exceptions. Some of the above mentioned
authors (Johnson, Rao, 1971; Ghosh et al., 1978; Ghosh, Paweletz, 1984)
try to find the reasons for these “exceptions” in differences in size, nature
and origin of the nuclei, non-optimal conditions of the nutrative regimen, in
metabolism, compartmentalization of the cytoplasm and their like.
Until recently the observed cytological pictures of asynchronous
division caused a perplexity. In his book “Mitosis and Physiology of Cell
Division” D. Mazia (1963) considers “unusual phenomenon” the
registered by Haque (1953) asynchronous division of nuclei in one of the
two binucleate cells, representing pollen grains of Tradescantia paludosa
(Fig. 3–28). In confirmation of his opinion he cites the words of Holden
and Mota (1956) that “even in unusual cases, when two nuclei in the cell
undergo mitotic divisions with a different speed, they can enter in
prophase simultaneously”.
image
image
Figure 3–28. Synchronous (A) and asynchronous (B) mitosis in binucleate pollen grains of Tradescantia paludosa (After Haque, 1953; From Mazia, 1963).
Peshkov and Rodionova (1964) have also registered a cell with two
nuclei, which are in different phases of division. After that Peshkov (1966)
analyzing the peculiarities of cytology and karyology of some unicellular
and multicellular green algae considers a mistake the interpretation of this
figure, given in their earlier work, where they have described it as a single
metaphase plate, and actually these are two separate groups of
chromosomes in different mitotic phases. As a result of this analysis he
has supposed that in Chlorella vulgaris during the transition to prophase
the mitotic division can proceed asynchronously. Nevertheless, after that
this great researcher emphasizes that divisions occur synchronously, one
after another, passing through the individual mitotic phases up to the