On the structure of pork tapeworm


All tapeworms parasitize in the gastrointestinal tract of the host, but the structure of the pork tapeworm has features that distinguish it from others. The presence of special hooks and suckers allows the soliter to firmly attach to the epithelial tissues and parasitize the intestines for a long time. These helminths can grow up to 8 m, and their average length reaches 2-3 m. They absorb nutrients and poison the body of an animal or person with toxic waste of their vital activity.

The parasite with a complex development cycle

Pork tapered Latin name which Taenia solium, is a source of infection with dangerous diseases teniozom and cysticercosis. This biohelminth has a complex life cycle, coupled with a number of changes in its structure that occur throughout life. The adult looks like a long white ribbon.

The intermediate larval form develops in the muscle fibers of pigs, dogs, camels, hares and rabbits. A person can also be a carrier of parasite larvae.

Infection of the carrier with a tapeworm occurs by eating the meat of animals infected with cysticercus.

The adult tapeworm is white in color. It lives in the human small intestine and consists of approximately one thousand segments. All segments of the tapeworm body have their own reproductive system and can produce up to 50 thousand eggs, giving rise to the development of larvae.

Together with the fecal masses, the parasite eggs are brought out. They are spread by small animals, infecting food and water sources, and then re-enter the gastrointestinal tract of the intermediate carrier.

You can learn more about this by reading the article "The life cycle of pork tape development."

Hooked Scolex

Scientific taxonomy classifies pork tapeworm to helminths with the classification of Cestoda parasitic tapeworms, which today are known to more than 3.5 thousand species. Type Plathelminthes - flatworms.

In the course of evolution, this helminth maximally simplified the structure of its body, adapting it to the parasitic way of life and now looks like a white thin ribbon.

The adult tapeworm has a small head (the scolex), which facilitates the attachment of the parasite to the epithelial tissue, nutrition, and the release into the external environment of the products of its vital activity.

The scolex of pork tapeworm has a length of about 3 mm and a diameter of up to 1 mm. There are four muscular suckers on it, allowing the parasite to stick to the intestinal wall of the host. Suckers are surrounded by a special proboscis or Rostellum, with which the parasite absorbs nutrients.

Unlike other tapeworms, the organ of attachment in the pork tapeworm has additional devices that allow it to fasten securely to the walls of the small intestine. From 17 to 32 prickly hooks are located on top of Rostellum, creating two rows of fixation devices.

It was the swivel hooks of the scolex that gave this species of parasite an additional name - armed chain.

The neck forms thousands of proglottids

Immediately behind the scolex is the neck, having a length of about 1 cm, producing a huge number of segments or proglottids. During life, they increase in size, self-fertilize and produce up to 50 thousand helminth eggs each.

New segments in length less than in width, but closer to the tail of the parasite, they become more oblong. During the day, the neck forms up to 5-6 new segments, and the helminth body length increases by 8-10 cm. Each hermaphroditic segment of the pork tapeworm is an independent living unit in which eggs are formed and fertilized.

The average length of an adult tapeworm is 2-3 m, although there are cases when the adult parasite reaches a length of 8 m. This is achieved due to the fact that mature proglottids, known as strobila, regularly come off the end of the worm. The number of detached daily strobile corresponds to the number of newly formed cervical segments.

Segments of the body of pork tapeworm are not adapted to movement. They passively move through the intestines of the host, along with fecal masses. In the external environment, eggs are spread by rodents, along with food entering the gastrointestinal tract of the intermediate carrier. Most often these are wild and domestic pigs that feed on waste products and tear apart the top layer of soil contaminated by worms.

Parasitism leads to a simplification of the body.

Due to the fact that the pork tapeworm is parasitic in the carrier's body, its digestive system is maximally reduced. Food is the walls of each proglottids. It is perfectly adapted to life in the small intestine of a person with a large amount of nutrients and low levels of acidity.

Nutrition and digestion of the pork tapeworm occurs continuously, and the nutrients consumed are spent on the production and development of new proglottids.

The nervous system of the tapeworm consists of a head node and two nerve trunks, at the location of which symmetry is observed. Both pass through the whole body parallel to the system of excretion The helminth has practically no organs of sense, and its breathing is carried out anaerobically.

The excretory system of the parasite consists of four thin tubules, stretching along the entire length of the worm's body and converging in the area of ​​the head. The anus of the worm is missing. All toxic substances that are formed in the process of life of the pork tape, flock through the excretory channels in the scolex. They are displayed in the intestinal wall of the host, infecting and poisoning it.

Toxic waste causes carrier poisoning.

It is a large number of toxic substances that enter a person infected with the pig chain of a person leads to painful sensations and the appearance of:

  • dizziness and headache;
  • weakness, lethargy and apathy;
  • nausea and gagging;
  • there is nervousness and temper;
  • reduced appetite;
  • constipation and diarrhea;
  • acute non-systemic pain in the abdomen;
  • with cysticercosis, a rash and a discharge on the mucous membrane appears.

During treatment, it is necessary to take into account the structural features of this parasite, which, with its hooks, extremely tightly clings to the walls of the small intestine of the host and, with mechanical tearing, can cause a small ulcer to appear. The back of the worm does not have hooks and can move freely with food passing through the intestines, and with mechanical damage it comes off, maintaining the vitality of the parasite.

Read more in the article "Ways to treat pork tapeworm".

Chitin shell protects against temperature extremes

Throughout life, proglottids develop female and male reproductive organs. Fertilization of eggs occurs in each strobil, measuring 12-15 by 6-7 cm, which creates virtually unlimited possibilities for reproduction of the worm. The mature segment of the pork tapeworm breaks away from the maternal organism and enters the external environment, where it can give rise to the development of tens of thousands of parasite larvae.

Each egg has a dense chitinous shell, the structure of which reliably protects it from negative environmental factors. Eggs perfectly tolerate heat and cold, maintaining their vitality even with prolonged freezing. They can be in the soil for a long time and transported by any living creatures, including earthworms, insects, birds, rodents.

Getting into their digestive system, worm eggs are not destroyed, but do not begin a new life cycle. For transformation into a larva it is required that the egg should fall into the gastrointestinal tract of a wild or domestic pig, dog, camel or man, the acid composition of which allows the chitin sheath to dissolve and release the larva.

Larvae have hooks for attaching to tissues

From time of birth, the larvae of the pork tapeworm that have emerged from the egg have powerful hooks with which they pierce the intestinal wall of the host, penetrating into its blood or lymphatic system. Together with the bloodstream, the larvae spread throughout the body, entering the muscle tissue and its internal organs.

Within 2-4 months, the parasite feeds the host with nutrients. Larvae reach the size of rice grain. They look like bubbles with a clear liquid.

The next step is the self-encapsulation of the helminth. It is covered with a layer of durable chitin, and inside it is a fully formed scolex, which has suckers, hooks, and a rudimentary neck, ready to immediately begin the production of proglottids.

The larva in the form of a cysticist may live for several months in the host’s muscle tissue, after which it dies.

In the human body, belonging to the final and dead-end branch of the parasite's development, tapeworms get together with foodstuffs that have not been heat treated. Pork tapeworm is distributed along with the meat of wild and domestic pigs.

Under the action of the acidic environment of the stomach, the cysticercus membrane is destroyed, and the young individual enters the small intestine. It attaches to the epithelium and begins to grow rapidly, absorbing the nutrients of the host, and its neck forms new proglottids.

Himself and mom and dad

The main feature of biohelmints is the simplification of their general structure, associated with the parasitic lifestyle in the host organism. They are virtually independent of changes in the environment, limiting their vital functions of nutrition, the release of toxic waste and reproduction.

Reproduction of the parasite is the responsibility of the reproductive system, which is of the hermaphroditic type. In the parasite there are male and female genitals. At the initial stage of development of the tapeworm, until its length reaches 1 m, only male cells develop in proglottids, and only after that the female reproductive system is formed.

Male genital organs are represented by numerous testes, having the appearance of small bubbles. They produce a large number of sperm, which fertilize the eggs.

Fertilization takes place inside the worm.

Numerous tubules run away from the testes, merging into the seed tube that is common to each proglottosis, which flows into the copulatory organ.

The formation of eggs occurs in the trilaterals ovaries, and their fertilization and accumulation takes place in the uterus, which has the form of a long hollow tube that runs along the entire length of the segment.

Such a structure of the reproductive system allows the soliter to produce eggs until the strobila detaches from the maternal organism.

Observance of sanitary and hygienic standards, which require that you always wash your hands after using the toilet and before eating, can protect a person from being infected with the eggs of this dangerous parasite, which causes cysticercosis. And the use of carefully heat-treated meat will prevent the ingress of larvae that cause the growth of tapeworm, which adversely affects the health of its host. Read more in the article "Pork tapeworm: ways of infection and symptoms."

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