The Ultrastructure of the Kinetochores ofLilium LongiflorumDuring the first Meiotic Division

Abstract

The kinetochores of the first meiotic divisions of Lilium longiflorum appear less electron-dense than the majority of the chromatin, are roughly spherical, and consist of fine fibrils 10–20 nm in diameter. The fine structure observed here appears to be consistent with several previous studies by other workers on higher plants. However, many variations in the observed fine structure of kinetochores of both plants and animals appear in the literature. Possible sources of the discrepancies in the observations are variations in interpretation of electron micrographs, variations in fixation procedures, and variations due to genuine phylogenetic differences of the organisms studied. Approximately 150–200 chromosomal spindle microtubules were estimated to end in each metaphase I kinetochore. Continuous spindle microtubules extend across the metaphase plate, passing between the bivalents, between the homologues of a given bivalent, and with some piercing the chromosome arms.