 The anthelmintic dinitroaniline arryzolin interferes with the formation of microtubules and inhibits meiosis and mitosis in nematodes. Exposure to arryzolin resulted in deterioration in morphology of the oocytes and loss of synaptonemal complexes at myotic prophase I. The nuclear matrix and envelope were poorly formed and the central rages was diminished. These results provide the basis for the loss of fecundity after treatment with the arryzolin resulting in control of parasitic nematodes. This article was authored by Paul Goldstein and said O. N. Caliskaner.