Abstract
The nematode Caenorhabditis elegans normally exists as one of the two sexes: self-fertilizing hermaphordite or male. Development as hermaphrodite or male requires the differentiation of each tissue in a sex-specific way. In this review, I discuss the genetic control of sex determination in a single tissue of C. elegans: the germ line. Sex determination in the germline depends on the action of two types of genes:-those that act globally in all tissues to direct male of female development and those that act only in the germ line of specify either spermatogenesis or oogenesis. First, I consider a tissue-specific sex-determining gene, fog-1, which promotes spermatogenesis in the germ line. Second, I consider the regulation of the hermaphrodite pattern of germ-line gametogenesis where first sperm and then oocytes are produced.