HeLa-cells, etc. In these cells the cell division is realized according to other
“rules”, differing from the normal ones. The reasons for that are complex,
most of them are not clearly explained. Reasonably, these cases can be
considered abnormal or pathological.
image
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Figure 3–17. Nuclear division in the dinoflagellate alga Gyrodinium cohnii (A) and a model of tridimensional reconstruction of the nucleus (B). (After Kubai and Ris, 1969). mt — microtubules; 1, 2 — chromosomes in contact with the nuclear envelope; Cy — nuclear remains; Cp — polar end.
The key to elucidating the cell division as a process lies in revealing the mode
of realization the nuclear reproduction and the chronology of forming daughter cells
in the mother cell. In biology the prevailing concept is that the division of the nuclei
and cells occurs synchronously, through realizing several consecutive cycles of
nuclear divisions. As a result of them there are formed new nuclei and daughter
cells, at that their number always is divisible by two (2ⁿ), where n means number of
division cycles. The concept of universality of the synchronous division has been
expressed concisely in the supposition of Koller (1947) that “synchrony is a constant
rule for all cells” (cited by Ghosh et al., 1978).
Investigations on unicellular green algae of Scenedesmus and Chlorella
genera (Nicolov, and Nicolov et al., 1982—1997 a) show that nuclear and cell
reproduction is realized asynchronously. Reasons for such conclusion are the
uneven number of nuclei (Figs. 3–18—3–20) and daughter cells (autospores)