A Pycnopodia oocyte. Image courtesy of George von Dassow, Center for Cell Dynamics, Univ. of Washington.

During oogenesis dramatic changes take place within the oocyte as it enters meiosis. Because sea urchin eggs complete meiosis before being shed, they are less convenient for studying meiotic maturation. Starfish oocytes, on the other hand, complete meiosis only upon suitable hormonal stimulation, and so they are very useful for studying the cellular and molecular mechanisms of meiotic maturation. One key event in meiotic maturation is germinal vesicle breakdown (GVBD), which marks the onset of meiosis I. The movies on this page show GVBD in starfish oocytes. The first is a Nomarski movie of GVBD in a Pycnopodia oocyte (courtesy George von Dassow, Center for Cell Dynamics, Univ. of Washington). The second visualizes GVBD in the bat star, Asterina miniata, using a fluorescent dextran. When the nuclear envelope breaks down, the dextran can enter the nucleus (courtesy Mark Terasaki, Univ. of Connecticut and Jan Ellenberg, EMBL, Heidelberg).

GVBD in a Pyncnopodia oocyte (5.4 Mb)
GVBD in Asterina visualized using dextran (1.3 Mb)