Nerve cells or neurons have a body, containing the nucleus, and a long tail or axon. In Nematodes, most nervous cell bodies are found in a ring formation around the pharynx, an organ part of the digestive system. From there, the cells' axons form four nerves that extend along the body. Nerve cells are responsible for the movement and sensory perceptions, such as temperature and light.
Nematodes have long muscle cells under their skin, which is not made of real cells, but a structure called syncytium containing many nuclei and a mass of cytoplasm. Muscle cells appear longitudinally aligned along the body. Muscle cells form organs of the digestive system, such as the pharynx and the intestine.The muscle cells are connected to two nerves, which together promote movement.
Coelomocytes are the immune cells found in nematodes and other invertebrates, such as insects and snails. Adult nematodes, such as the free-living Caenorhabditis elegans, have three pairs of coelomocytes, located in right, left and dorsal areas. Only four coelomocytes are present at the nematode's hatching. These immune cells can perform phagocytosis, like some cells of vertebrates, engulfing and destroying the invading microbes.
Although most nematodes have separate sexes, some species are hermaphrodites, producing both male and female sexual cells. Nematodes' have one or two gonads, organs in a tube-shape that produce the male sexual cells, spermatozoids, or the female sexual cells, oocytes. The largest cell in a nematode's body is the excretory cell, which is connected to a pore located in the head, where ammonia and other waste substances are eliminated.