Progressive disassembly of the mitotic spindle into two halves at anaphase and assembly of an astral neo-spindle during cleavage mitosis in the newt embryo.

In the second cleavage mitosis of newt embryos at anaphase, disassembly of mitotic spindle fibres, mediated by the 'plus' ends of their microtubules, results in equatorial division into two half-spindles. Yolk-filled cytoplasm invades the area free of fibres and is itself penetrated by antiparallel fibres from asters, which have become nucleated at opposite poles. These fibres immediately supplant the mitotic spindle; they participate in the lengthening of the interpolar distance and in the positioning of the newly formed daughter nuclei.

Enhanced polyploidy by glutaraldehyde in cultured HL60 leukemic cells.

Glutaraldehyde 10(-4) M weakened cell proliferation of HL60 cultured cells and enhanced the appearance of giant polyploid cells, up to 32.5% after 6 days. The size and structure of these cells, the quantitative changes in their DNA content with respect to diploid ones demonstrate their polyploid nature, which may be corrected by the occurrence of pluripolar mitoses.

[Effect of methylmercury chloride on mitosis in human lymphocytes in culture: ultrastructural study].

The ultrastructural study of proliferating human lymphocytes poisoned by methylmercury chloride, shows that this product disorganizes and alters the different constituents of the mitotic figure. The chromosomes, partially decondensed, are covered with protuberances and connected by various chromatin bridges. Tubular structures are changed.

Transformation, remodeling and dissociation of achromatic fibres by butyric acid in mitoses of cleaving eggs. Effects of associated antitubulin substances.

A mM solution of butyric acid transforms the achromatic apparatus of segmentation mitoses: asters are reduced or suppressed, cytokinesis is inhibited before mitosis, spindle fibers are broken and fan out progressively in the equatoria; region becoming radially oriented instead of axially. The results are either: 1) hollow fibrillar systems, 2) radiating spindle systems, apparently pluripolar, 3) dissociated fibrillar systems, depending on the phase of the mitotic cycle in which the butyric acid acted. Colchicine 2.

[Comparative hepatic toxicity of perhexiline maleate and griseofulvin in mice].

Hepatic toxicity was observed in mice which had received Griseofulvin or Perhexilin Maleate over a period of several months. Treatment of griseofulvin alone gave rise to hepatitis with the presence of Mallory bodies (MB) whereas the same length of treatment with Perhexilin Maleate was associated with steatonecrosis with an absence of MB. When treatment was followed by a one month rest period hepatic lesions disappeared with no trace of sequelae.