Once in the spermatheca, the spermatids are rapidly activated into spermatozoa (sperm), and one of them fertilizes the first oocyte. Ovulation of the first −1 oocyte pushes the previously produced spermatids out of the proximal gonad into the spermatheca. The mature, fertilization-ready oocyte resides at the most proximal region (−1 position) of the gonad ( Fig. Germ cells that are differentiating into oocytes are aligned in the adult worm gonads, so that immature cells are relatively distal ( Fig. Hence, adult hermaphrodites are somatically females, although they contain self-sperm. When L4 hermaphrodites become young adults, spermatogenesis stops and both arms of the U-shaped gonad completely switch to oogenesis. Hermaphrodites first undergo spermatogenesis during the fourth larval (L4) stage. elegans has a male like most animals, but it lacks a true female and instead has a hermaphrodite where both spermatogenesis and oogenesis occur ( Hirsh et al., 1976). elegans male germline functions are also reviewed elsewhere ( L’Hernault, 1997 L’Hernault, 2006 Singson et al., 2008 L’Hernault, 2009).Īs shown in Fig. elegans spe genes play roles during spermatogenesis (spermatid production), spermiogenesis (spermatid activation into spermatozoa), and/or fertilization. elegans genes required for reproduction have been identified, and ~60 genes that can mutate to cause defects in male germline functions, the so-called spermatogenesis-defective ( spe) genes, are included among this group ( L’Hernault, 1997 L’Hernault and Singson, 2000). The nematode Caenorhabditis elegans is an excellent model system to investigate a variety of biological phenomena, including reproduction ( Brenner, 1974). A mature sperm and oocyte subsequently fuse during fertilization to produce a diploid zygote that is the progenitor of all somatic and germ cells. During gametogenesis, germ cells differentiate into either sperm (spermatogenesis) or oocytes (oogenesis). Germ cells are essential to create the next generation of most multi-cell organisms via gametogenesis followed by fertilization.
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