Segregation of germline granules in early embryos of Caenorhabditis elegans: an electron microscopic analysis.

Using an improved fixation method for electron microscopy, we have found germline granules in Caenorhabditis elegans embryos shortly after fertilization and prior to the first cleavage. They are localized in the egg cytoplasm which becomes segregated into the posterior blastomere at the first cleavage. In the following divisions, the granules continue this pattern of asymmetric segregation and are ultimately segregated into the germline precursor cell. The granules are then symmetrically segregated into the germline cells.