Spindle Imaging in Living Mammalian Oocytes Using the Liquid-Crystal Polarized Light Microscope and Its Practical Use

Ovulated oocytes in most mammals are arrested in metaphase II, at which point a dense array of microtubule filaments and bundles form the meiotic spindle. The spindle is vital to the alignment and separation of the chromosomes along the metaphase plate so that a proper division of the chromosome pair can occur during meiosis. Abnormalities in its integrity may be related to failed or abnormal fertilization. The architecture of the spindle’s filamentous network is dynamic and can be used to understand the changing biology of the oocyte in vitro. It is also a potentially fragile structure, and, as a practical matter, techniques for visualization of the spindle can prove effective in studying dynamics of the spindle. Most conventional high-resolution methods for observing the spindle, such as immunocytochemistry and transmission electron microscopy, rely on fixation and staining procedures, so they are of limited value in clinical application and in studies of spindle dynamics.