Marine oocytes and embryos have long been favored systems for the study of cell division and the cytoskeletal dynamics that accompany karyokinesis and cytokinesis. Several characteristics make marine egg systems ideal for the study of cell replication including: 1) the clarity of the eggs, which allows excellent real-time visualization of cytoskeletal components; 2) the natural synchrony of the cells, because the oocytes are typically arrested at a specific phase of the cell cycle until fertilized or artificially activated; 3) the rapid and synchronous cell divisions that follow fertilization or activation; and perhaps most importantly, 4) the large quantities of oocytes that can be obtained. Here we describe an in vitro system that utilizes cytoplasmic extracts prepared from surf clam,Spisula solidissima, oocytes for the analysis of the microtubule cytoskeleton during meiosis I spindle assembly.
