Morphogenesis in a green alga, Micrasterias

Abstract

Summary: After cytokinesis, the septum protorude a daughter half cell which is at first bulge formed and later develops into 3, and 5 lobes. Daughter half cells incresed in volume due to water penetration resulted from the decrease in the wall pressure of young half cells. Young half cells stopped growth in isotopic or hypertonic solutions, and small half cells were obtained. The irregular shaped small half cells produced normal shaped and normal sized descendant cells. Double cells produced anucleate cells or multinucleate cells, by which the role of the nuclei and of the cytoplasm in the morphogenesis was analyzed. Plasmolysis was not seen at the concave regions of the lobes. It is speculated that this regions stopped the out growth by inhibiting of Golgi vesicles to pass through the plasma menbrane.The localization of microtubules implies that they porevent the spheriacal expansion of lobes. The two factors, the connecting substancs at the concave regions and the microtubules, seem to regulate the morphogensis in Micrasterias.