This paper is a collective review of the reports (Wada 1935-1974) previously published to corroborate the atractoplasm theory proposed by Fujii (1931) and it also offers a consolidated interpretation of the morphogenesis of mitotic spindles in eukaryota based on comparative studies on protista, metazoa and metaphyta.
From the results of these investigations the author points out that the common idea of the breakdown of the nuclear membrane as one step in the spindle formation in higher plant and animal cells is a gross error. The reasons and the complications by which this error had been overlooked for nearly a century are explained and discussed from various viewpoints, such as the imperfection of observation techniques, the nature of the research material, considerations of evolution relationships, and gene information on the morphogenesis of mitotic spindles in eukaryota.
The author makes clear that many unsolved problems and controversial interpretations of mitosis described in current cytology books are mostly attributed to the misinterpretation of the nuclear membrane in mitosis. He has given answers to these problems.
The morphological independence of mitotic spindles from the cytoplasm, and the transfiguration of metabolic nuclei into karyokinetic ones can be expressed as follows:
The metabolic (resting) nucleus, spherical in form composed of 1) chromonemata, 2) nucleoli, 3) nuclear sap (dispersed globular proteins), and 4) nuclear membrane.
The karyokinetic nucleus (metaphase spindle), spindle-shaped in form composed of 1) chromosomes, 2) kinetochore fibers, 3) atractoplasm (arranged fibrous proteins), and 4) nuclear membrane (a strained state due to enlargement of nuclear volume in the case of higher plant and animal cells).
The morphological continuity of mitotic figures and the cause and effect relations among them are explained in detail from prophase nucleus through metaphase spindle to the appearance of daughter nuclei in telophase, including chromosome movement in anaphase. The biological significance of the spindle-form of karyo-kinetic nuclei for the mechanism of mitosis is explained.