An ultrastructural examination of the action of vinblastine on microtubules, neurofilaments and muscle filaments in vitro

An electron microscopic study of the effects of vinblastine sulphate on the ultrastructure of the kidney, trachea, liver, peripheral nerve and small intestine of the rat

The effects of vinblastine in high doses on the kidney, liver, trachea, peripheral nerve and small intestine of rats have been studied by scanning and transmission electron microscopy. Dramatic structural changes were seen in glomerular visceral epithelial cells, hepatocytes and small intestinal epithelial cells which appear to be due to the effect of vinblastine on microtubules and possibly also on other proteins and cell membranes. Ciliary microtubules appeared resistant to vinblastine effects.

Extracellular microtubule-like structures in the retina of the rainbow trout: development, intercellular connectivity and reaction to vincristine

Extracellular microtubule-like structures (MLS) are described in the retina of the rainbow trout. They appear about 30 to 40 days after hatching, when the yolk-sac is consumed and the animal begins to swim and to nourish actively. They fill a widely branched system of extracellular clefts and spaces, and connect different cells and cell types, especially outer horizontal cells and bipolar cells. The MLS are not affected by the vinca alcaloid vincristine, although this drug penetrates into the MLS-filled space, as has been shown by the formation of intracellular, vincristine-induced tubulin paracrystals. The MLS are compared with other extracellular tubular structures described in other animal tissues. Their functional significance remains unclear.

Observations on the disassembly of isolated mammalian neurofilaments

Intact mammalian neurofilaments were separated by centrifugation of osmotically shocked, desheathed segments of rat peripheral nerve. Neurofilament-rich supernates were incubated in different media with varying dilutions or dialysis of samples. Neurofilaments attached to carbon-Formvar-coated grids were exposed to similar incubations. The relative preservation or disruption of neurofilaments during different incubational conditions was monitored through periodic examinations of neurofilaments by negative staining techniques. Maximum structural stability of neurofilaments was manifested during incubation in isotonic NaCl or KCl. Decreasing salinity of incubational media led to increasing disruption of neurofilaments, especially in solutions less than 0.01 M. Hypertonic saline solutions were found to be less disruptive to mammalian neurofilaments. Additional studies examined neurofilamentous alterations effected by pH, protein denaturants, mitotic spindle inhibitors, reducing agents, and freeze-thawing procedures.