Presents the events of meiosis I in a living spermatocyte obtained from the testis of a crane-fly larva are recorded in this time-lapse sequence beginning at diakinesis through telophase to the near completion of cytokinesis following meiosis I. Noteworthy features of meiosis in crane-fly spermatocytes: a) The duration between nuclear envelope breakdown (NEB) and the onset of anaphase lasts on average about 75 to 80 minutes. b) Upon NEB, birefringent microtubules invade the space previously occupied by the nucleus, and some of these attach to the kinetochores of bivalent chromosomes. c) Also at NEB, the two sex chromosomes, paired prior to that time, precociously disjoin and exist as univalents throughout meiosis I. d) Kinetochore fibers appear distinct due to their birefringence, which is readily detected with polarized light microscopy. e) At metaphase, the spindle has a characteristic bi-cone shape, and its kinetochore fibers have striking bright birefringent contrast. f) Anaphase A (kinetochore fibers shorten) is the predominant component of anaphase in these cells; anaphase B (spindle elongation) makes a minor contribution to chromosome segregation. g) Sex chromosome anaphase is delayed as a consequence of their amphitelic orientationComponente Curricular::Educação Superior::Ciências Biológicas::Biologia Geral