Abstract
Whether the function of a gene is required in a given cell type is often determined through the analysis of clones homozygous for a mutant allele of the gene. The clones usually develop following X-ray induced mitotic recombination. The paper summarizes the conclusions of clonal analyses of different types of mutations in both the epidermis and the female germ line cells of Drosophila. Principles of the so called dominant female sterile technique -for the germ line and the follicle cells- and its use are summarized. Special attention is paid to the genetic requirement of the female germ line due to its fundamental function in the regulation of early embryogenesis.
