Fasciola Hepatica and Taenia Solium| Phylum Platyhelminthes

Learn about the comparison between Fasciola Hepatica and Taenia Solium.

Comparison # Fasciola Hepatica:

1. Fasciola Hepatica is found in Asia, America, Europe, Africa.

2. Fasciola Hepatica live in the bile duct of the liver of sheep, cows, pigs, etc. and occasionally found in man. Larval forms occur in snail.

3. Body of Fasciola Hepatica is flat and leaf-like, size varies from 1.0 to 2.5 cm in length, width is about 1 cm. Anterior end is conically projected to form the ‘head lobe’. There are two suck­ers.

Anterior sucker is situated at the apex of the head lobe—the ventral sucker is situated ventrally and little below the head lobe. Single median genital pore is situ­ated ventrally and in between the two suckers. Single excretory ap­erture lies at the extreme posterior end of the body. A thick cuticle bears spine-like thickenings.

4. Mouth of Fasciola Hepatica lies in the middle of ante­rior sucker and is followed by a suctorial pharynx. Oesophagus is short and soon bifurcates to form the intestine. Many caeca originate from the main branches almost in every region of the body. There is no anus.

5. The main excretory canal opens to the exterior through an aperture situated at the posterior end of the body. The duct receives many tu­bules each of which ends in flame bulb.

6. Nervous system of Fasciola Hepatica consists of prominent masses, called cerebral ganglia, joined together by a nerve ring around the oesophagus. From the ganglia nerves are given off to the head lobe and to the posterior part of the body. One pair of these poste­rior nerves is larger and more stout than the others.

7. Individuals are hermaphrodite. Sex organs are well-developed. The male organs consist of a pair of much branched testes, two vasa deferentia, a pear-shaped seminal vesicle, a convoluted ejaculatory duct and a muscular penis (cirrus).

Female organs consist of single and branched ovary, a convoluted oviduct, shell gland, a uterus, which leads to the genital pore. Accessory glands—yolk or vitell­ine glands open through ducts in the shell gland. A canal called Laurer’s canal running between the point of fusion of vitelline duct and oviduct at one end and the dorsal surface at the other end. Cross-fertilization is the rule.

8. Life history of Fasciola Hepatica:

(a) Fertilized eggs develop into ciliated Miracidium larva and it forces its way into the snail’s body.

(b) Miracidium changes to Sporocyst within which Rediae are developed.

(c) Rediae produce daughter Re­diae.

(d) Rediae (daughter) give rise to Cercariae which leave the snail’s body and on reaching its primary host (sheep) de­velop into adult flukes.

Comparison # Taenia Solium:

1. Taenia solium is found world-wide.

2. Taenia solium lives in the alimentary canal of man, ‘cyst’ forms occur in pig.

3. Body of Taenia solium is flat and ribbon-like, consist­ing of a knob-like head or ‘scolex’ and a great number of similar parts, called proglottids, arranged in a single row. A short neck remains in between the scolex and the proglottids. Proglottids gradually increase in size from anterior to posterior.

An individual may attain a length of 3 metres and number of proglottids may be about one thou­sand. The scolex bears at its tip a rostellum with double rows of curved chitinous hooks and four suckers.

4. There is no alimentary canal in Taenia solium, absorption occurs through general body wall predominantly by diffu­sion.

5. In each proglottid houses many flame-bulbs are arranged superfi­cially and having drainage tubules. These tubules of Taenia solium carry the excretory products to two longitudinal ca­nals placed laterally. These lateral canals are joined by transverse ca­nals. The ends of the lateral canals act as excretory pores.

6. The scolex bears a transverse band of nervous material. This ganglionated mass gives out slender branches to the suckers and to the posterior parts of the body. Two stouter nerves run laterally along the long axis of the body.

7. Individuals are hermaphrodite. Sex organs are repeated in each proglot­tid. A mature proglottid is almost filled with sex-organs. Male organs consist of numerous testes, efferent ducts, vas deferens and a protrusible penis (cirrus) lying in the genital atrium located on one of the lateral borders.

Female organs consist of ovary which is bilobed and situated at the hinder end—a short oviduct, and vagina which opens into the geni­tal atrium. Uterus is much branched and originates from the base of the oviduct. A median and compact vitelline gland and a shell gland surround the base of the uterus and oviduct. Laurer’s canal is ab­sent.

Self-fertilization takes place.

8. Life history of Taenia solium:

(a) Fertilized eggs develop into six- hooked Heacanth larva while still within the proglottid.

(b) On reaching the pig they force their way into the voluntary muscle and form cysts.

(c) The wall of the cyst gives rise to a head and is known as Cysticercus at this stage.

(d) On reaching man the Cysticercus gives off series of proglottid and becomes mature.