Vincristine is a cytotoxic tubulin binding agent, derived from the periwinkle plant, Vinca rosea Linn. It lia,- been known as a potent mitotic inhibitor that has found its place as effective drug in combination chemotherapy regimens for the treatment of human leukemias, lymphomas and a variety of solid tumors.
The major antitumor effect of this agent appears to be related to its high affinity of binding to the basic protein subunit of microtubules, tubulin, which results in disruption of the mitotic spindle apparatus and arrest cells in metaphase. Vincristine also acts on normally proliferating cells.
The author has investigated the effect of vincristine on the chief cells of hamster, histologically observing the morphological changes in the cell by the use of light and electron microscopes. The animals treated with 2.5mg per kg of vincristine were sacrificed at 12 and 24 hours after the drug administration. The animals of control group were administered only water for injection. All animals were starved for 12 hours before sacrificing them. A part of stomach specimens was fixed in 10% neutral formalin and prepared by way of hematoxylin and eosin stain and the other part of specimens, which was prefixed in 2% glutaraldehyde-2.5% paraformaldehyde phosphate buffer and post-fixed in the 1% osmic acid, was dehydrated and embedd-
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ed in the Epon 812. Ultrathin sections, 600-800 Athickness, were made and double stained with uranyl acetate and lead citrate. And these preparations were observed with light and JEM 100 cx-II electron microscopes.
The results were obtained as follows;
1. The dilatation of the glandular lumens due to degeneration and atrophy of lining cells of gastric gland was observed. Vacuolar degeneration, faint cellular boundary, pyknosis and karyolysis were seen in the chief cells at 24 hours after drug administration.
2. In the chief cells, pronounced dilatation, sacculation and fragmentation of the cisternae of rough endoplasmic reticulum were associated with detached membrane bound ribosomes and cisternae were decreased in the course of time. Fused irregular zymogen granules in the supranuclear region, many lysosomes and numerous autophagic vacuoles were observed in the cytoplasmi.
Consequently, it is suggested that intraperitoneal injection of vincristine would in-duce degenerative changes of cytoplasmic organelles of the chief cells of hamsters.
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