Microtubule organization in developing rat oocytes were investigated through confocal microscopy. The inductive effects of some factors on microtubule modification were also studied. The results indicated that the meiotic cell cycle progression of rat oocyte is accompanied by extensive rearrangement of the microtubule network of the cell. Microtubule organization was modified by the treatment of oocytes with taxol, staurosporine, or okadaic acid. Rat oocytes released from the oviducts could undergo spontaneous parthenogenetic activation. They could also be induced to pseudo-cleave by cytochalasin B treatment. The microtubule configuration in rat oocytes undergoing spontaneous parthenogenetic activation or pseudo-cleavage was also observed.