Caenorhabditis elegans, the nematode worm, is a small, structurally simple organism whose developmental anatomy is well characterized, enabling the creation of an intricate cell lineage map. Understanding genetic regulation in multicellular organisms is greatly aided by this opportunity, as it comes with a known genome sequence and multiple investigated mutant phenotypes. But its complexity—roughly 18,000 genes and 1000 cells—means that computer support is necessary. Even though it doesn't have eyes or limbs, the worm is a useful model to learn about basic concepts in animal development. Notwithstanding obstacles such swift changes in evolution and restricted applicability to specific organ formation research, C. elegans enables us to investigate these issues at the cellular level, providing understanding of the genetic processes guiding growth.
With roughly 1000 somatic cells and 2000–2000 germ cells, Caenorhabditis elegans possesses a streamlined body plan with bilateral symmetry in its adult form. Through serial slice electron microscopy, its anatomy has been meticulously reconstructed, cell by cell. Basic tissues including nerve, muscle, gut, and skin make up the worm's body, which is oriented with the anus at the rear end and the mouth and brain at the anterior end. An underlying layer of muscle and the protective epidermis make up the exterior body wall, while the gut is formed by an endodermal cell tube. Nestled between the gut and the body wall is a second tube known as the gonad, which contains both somatic and germ cells.
There are two sexes in C. elegans: male and hermaphrodite. The hermaphrodite acts like a female and releases a finite amount of sperm. It can procreate by either cross-fertilization—using male sperm received during mating—or self-fertilization—using its own sperm. For genetic investigations, self-fertilization is useful because it allows homozygous progeny to be produced from a single heterozygous worm. Because of this feature, C. elegans is especially useful for genetic study.
The life cycle of C. elegans begins with a single fertilized egg. The egg then divides into 558 cells, which together form a little worm inside the eggshell. After hatching, the worm grows and becomes sexually matures by subsequent cell divisions, going through four larval stages that are separated by molts. When the hermaphrodite worm reaches the adult stage and completes its last molt, it starts to lay eggs on its own. From egg to egg, the entire developmental process takes about three days.
References:
Comments