Liver fluke systems
The hepatic fluke is a parasitic worm that is able to live in the liver, gallbladder and bile ducts of humans and other vertebrates. The liver fluke causes a condition called fascioliasis. In structure, the hepatic fluke is similar to ciliary worms, but its main distinguishing feature is that it is a parasite. Liver fluke systems have the following features:
Content:
- Digestive system of the hepatic fluke
- The integuments of the body and the motor apparatus of the hepatic fluke
- The reproductive system of the hepatic fluke
- The excretory system of the hepatic fluke
- The nervous system of the hepatic fluke
Digestive system of the hepatic fluke
The mouth opening in hepatic flukes is located on the front of the body. The mouth looks like a sucker, from which a muscular pharynx extends. The pharynx is followed by the esophagus, and then the branched intestine, which ends blindly. Many branches leave the intestines. The mouth opening at the same time serves as an anus for the worm, through which it removes the products of its own vital activity.
The integuments of the body and the motor apparatus of the hepatic fluke
The hepatic fluke reaches 30-50 mm in length and 12 mm in width. The body is formed by the skin-muscle sac, and the outer cover is represented by neodermis. Nedermis cells fuse with each other to form syncytium. Underneath the neodermis is the basement membrane, followed by a layer of smooth muscle. Worms have longitudinal, annular and diagonal muscle fibers.
In order to attach themselves inside the body of their final host, the worms have special suction cups. In the liver fluke, this sucker is represented by a powerful muscular apparatus located on the peritoneum. An additional suction cup is the mouth, but with its help the parasite also provides nutrition, while the abdominal sucker serves only for fixation.
The body of the liver fluke is leaf-shaped. Its front end is drawn and resembles a beak. The leaf-like shape of the body allows you to fully supply the worm's body with useful substances.
The reproductive system of the hepatic fluke
The hepatic fluke is hermaphrodite. The male genital organs are represented by two testicles and vas deferens, the ejaculatory canal and the copulatory organ. The testes of the worm are highly branched. Male germ cells are formed in the testes, then they enter the copulatory organ through the vas deferens, which protrudes and penetrates the vagina of another parasite during mating.
The female genital organs are represented by the oviducts with the ovaries, vitellus, uterus and genital cloaca. Thanks to the vitellines, the egg receives nutrients. Cross-seeding, that is, this process requires the fusion of germ cells of different individuals. The eggs mature in the uterine cavity. After fertilization, the egg is covered with a dense shell. Melissa's bodies take part in its formation, which secrete a special liquid secret.
During fertilization, the worms connect in pairs and exchange male reproductive cells. They enter the uterus, then into the ootype (central chamber of the female reproductive system), where they merge with the oocytes. The formed egg enters the uterus and gradually moves towards the external genital opening. At this time, an embryo is formed inside the egg. When it ripens, the egg comes out. It has an oval shape, yellowish-brown color and sizes from 135 to 80 microns. For the larva to emerge, each egg is equipped with a small cap.
The excretory system of the hepatic fluke
The excretory organs are represented by a well-developed protonephridial system, which performs the functions of distribution and osmoregulation. The main excretory canal runs in the middle of the body of the hepatic fluke. The breakdown of complex substances into simpler ones in the body of the parasite is carried out anaerobic way.
The nervous system of the hepatic fluke
The appearance of the nervous system of the hepatic fluke resembles a lattice, which originates from the periopharyngeal nerve ring. From it there are 3 pairs of trunks, which are interconnected by small bridges. The lateral nerve trunks of the parasite are better developed.
Some organs of the hepatic fluke are simplified in structure, so, it completely lacks the circulatory system.
The main aromorphoses of worms of this species are in the following features:
- The presence of suction cups.
- Well-developed reproductive system.
- Complex life cycle of worm development.
- Intensive reproduction at almost all stages of the life cycle.
In addition to the fact that parasites lack a circulatory system, they do not have sexually mature sense organs. However, in the larval form (at the miracidium stage), the worms have eyes and cilia, which allow parasites to navigate in the external environment and actively move.
For full development from larva to adult, the hepatic fluke will need to change one intermediate host. It is a freshwater mollusk, after which the larva becomes invasive and can infect humans or animals.
Author of the article: Danilova Tatyana Vyacheslavovna | Infectionist
Education: in 2008 received a diploma in the specialty "General Medicine (General Medicine)" at the Russian Research Medical University named after NI Pirogov. Immediately passed an internship and received a diploma of a therapist.
