Abstract
The cytological effects of hydroxyurea (HU), an inhibitor of DNA synthesis, were examined on mitotic and meiotic divisions in lily micro-sporocytes. Microsporocytes in premeiotic stages and meiotic prophase were cultured in vitro for discrete periods in the presence of the inhibitor at various concentrations. Hydroxyurea interfered with mitotic development if admini-stered to cells during the late S or early G2 phase of premeiosis, when cells undergo mitotic division by explantation. When applied during leptonema, the main effects were the suppression of meiotic development and the produc-tion of sticky chromosomes. The affected cells progressed through early pro-phase without showing any gross cytological abnormalities ; the inhibition of DNA synthesis by hydroxyurea during zygonema did not interfere with synapsis. On further culture, cells did not progress beyond prophase; but remained suspended in some stage of lateprophase. Chromosome stickiness was the response of cells cultured with hydroxyurea during pachynema for a prolonged period. The relevance of these observations to microsporocyte development is discussed.
