| Abstract: | ![]()
Studies were made on which components of sperm were able to induce aster formation and cleavage of eggs of the sea urchin Hemicentrotus pulcherrimus. The sperm components were separated by homogenization and centrifugation into the following 3 fractions: the head-midpiece, midpiece and tail. The head-midpiece fraction was then divided into 2 sub-fractions, the centriole sub-fraction and the centriole-free sub-fractions. Each fraction was injected into unfertilized eggs and after 15–30 min the eggs were inseminated. The ability of a fraction or a sub-fraction to induce aster formation and cleavage was deduced from the frequency of multipolar cleavage. The head-midpiece fraction and the centriole sub-fraction were effective in inducing aster formation and cleavage, but the other fractions were not. It was concluded that isolated centrioles from sea urchin sperm act as division centers in the egg. |
