Some ultrastructural features of Volvox, with particular reference to the phenomenon of inversion.

Abstract

Some features of the ultrastructure of Volvox are described. Golgi bodies were often associated with the endoplasmic reticulum (ER), and the two basal bodies appeared to be accompanied by two probasal bodies. A few vegetative cells were binucleate. All cells examined had a peripheral cytoskeleton of microtubules which was particularly well developed in the cells of sperm packets. During inversion of a colony, the cells elongated considerably, possibly due to the increased length of these peripheral microtubules; the cell profile also became some-what narrowed at the inner edge of the flexing colony. Cytoplasmic connections were large and numerous in young coenobia, but were generally absent ..