It is connected via a pair of ducts to a number of vitelline glands on either side of the body, that produce yolk cells. After the egg is surrounded by yolk cells, its shell is formed from the secretion of another gland called Mehlis gland or shell gland, the duct of which also opens in the ootype. The ootype is connected to an elongated uterus that opens to the exterior in the genital pore, close to the male opening. Most commonly found in trematodes, the sperm cells travel through the uterus to reach the ootype, where fertilization occurs. The ovary is sometimes also associated with a storage sac for sperm, and a copulatory duct termed  Laurers canal. Laurer’s canal is described to be the primitive vagina but it is a vestigial organ in some species. In some instances it can serve as a tube outside the worm for potential waste products from the egg-formation system. Organ morphology
Body wall musculature: Formed of three different muscle layers: circular, longitudinal, and diagonal. The outermost layer is formed by the circular muscle fibers, directly behind that are the longitudinal muscle fibers. The inner layer is formed by the diagonal muscle fibers. Together these muscle fibers form the segmented body wall of trematodes.Oral sucker and acetabulum: In some species of Trematoda, such as T. bragai, there is an acetabulum. This saucer-shaped organ is attached to the oral sucker in some Trematodes and other parasitic worms.
Like other flukes, the liver flukes need intermediate hosts and as a result, the transmission from animals to humans happens in three phases. The first phase is the infection of the snail (the first intermediate host) via feces. They complete their gestation and hatch as cercariae. They leave their snail hosts and infect fish who are their second intermediate host. Lastly, humans ingest the metacercariae in raw and undercooked fish. In humans, the metacercariae complete their life cycle and become full grown liver flukes. Infections
Human infections are most common in Asia, Africa and Latin America. However, trematodes can be found anywhere where untreated human waste is used as fertilizer. Humans can be infected by trematodes either by consuming undercooked contaminated fish or plants, or by ingesting contaminated water. The metacercariae of trematodes attach to fish and plants. In addition, humans can be infected by certain species through swimming in contaminated water. Humans cannot get infected by trematodes directly, trematodes require an intermediate host to do so.Schistosomiasis (also known as bilharzia, bilharziosis or snail fever) is an example of a parasitic disease caused by one of the species of trematodes (platyhelminth infection, or "flukes"), a parasitic worm of the genus Schistosoma. Clonorchis, Opisthorchis, Fasciola and Paragonimus species, the foodborne trematodes, are another. Other diseases are caused by members of the genus Choledocystus. Medically, trematodes are often classed by which organ they invade, which can include blood vessels, the gastrointestinal tract, lungs, or liver.