Fruit flies have separate sexes and a sexual reproduction. Like males in many other animals species, fruit fly males have internal gonads that produce sexual cells or sperm. Members of the genus Drosophila produce sperm cells with long tails that coil around the female eggs. Also called gametes, sexual cells contain half of the DNA found in other types of cells. Fruit flies also have specialized cells in their gut, called stem cells. More common during the embryonic development of animals, these immature cells are also present in the adult fruit fly, playing an important role in the regeneration of gut tissues.
Fruit flies have nervous cells called neurons, which form their brains and nervous systems. The fruit fly has three types of neurons: afferent neurons, which are associated with sense organs; efferent neurons, which are connected to muscles and are linked to locomotion and hormonal production; and internuncial neurons, which are linked to both sensory and locomotive functions. Glia cells are often associate with neurons, and have a sensory function. In fruit flies of the genus Drosophila, these cells are found in the antennae and are linked to the sense of smell.
Fruit flies have strong muscles in their thorax, which are very important during flight. These cells are elongated and contain several nucleus. More than 3,000 cells can be found in a single muscle of a fruit fly. The epidermis is the outer layer cell of the fruit fly. Specialized epidermal cells called oenocytes secrete the cuticle that forms the exoskeleton of fruit flies and other insects.
Hemocytes are found in the hemolymph, which is the fluid of the circulatory system of most insects. Hemocytes are immune defense cells, and freely circulate around the body with the hemolymph. Excretory cells are called nephrocytes. These large cells filtrate the hemolymph, eliminating waste substances. The structure of nephrocytes is similar to the human podocyte, a cell located in the kidney.