Fasciola hepatica (The Liverfluke).pptx

Fasciola hepatica (liver fluke) is a platyhelminth (flatworm) that is bilaterally symmetrical, triploblastic and dorso-ventrally flattened. They are unsegmented and acoelomates. They are trematodes belonging to subclass digenea. Thus, they are endoparasites with two suckers without hooks.

1. Shri Shivaji Education Society, Amravati's Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly. Dist. Buldana Topic: Phylum Platyhelminthes Class: B.Sc-I, Sem-I Shantaram Bhoye Assistant Professor, Department of Zoology M.Sc., NET-JRF, SET, M.A.(Eng.)

2. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana Phylum Platyhelminthes General Characteristics: They are triploblastic, acoelomate, and bilaterally symmetrical. They may be free-living or parasites. The body has a soft covering with or without cilia. Their body is dorsoventrally flattened without any segments (Except in class cestoda ) and appears like a leaf. They are devoid of the anus and circulatory system but have a mouth. They respire by simple diffusion through the body surface. They have an organ level of organization. Skeletal, Respiratory and Circulatory systems are absent. The space between the body wall and organs is filled with connective tissue parenchyma which helps in transporting the food material. They are hermaphrodites, i.e., both male and female organs are present in the same body. They reproduce sexually by fusion of gametes and asexually by regeneration by fission and regeneration.  Fertilization  is internal. The life cycle is complicated with one or more larval stages. They possess the quality of regeneration. The flame cells help in excretion and osmoregulation. The nervous system comprises the brain and two longitudinal nerve cords arranged in a ladder-like fashion.

3. Fasciola hepatica : The Sheep Liver fluke: Liver flukes, also known as Fasciola hepatica, are parasites that cause the liver fluke disease known as Fascioliasis (Liver rot) in the liver of human beings. The liver fluke parasite falls under the phylum Platyhelminthes. The liver fluke disease is caused when immature liver fluke parasites migrate through the liver and are sometimes caused by the presence of bile ducts, or sometimes both. Liver fluke infects all grazing animals like sheep, cattle and mammals like human beings. Liver fluke parasites occur in regions around water bodies like river banks, slow streaming rivers, and irrigation channels, as all these areas are suitable for hatching eggs of the liver fluke. The infestation of these parasites in animals like sheep, and cattle have greatly impacted the agricultural industry. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

4. Classification: Phylum : Platyhelminthes Class : Trematoda Order : Digenera Genus : Fasciola Species : hepatica Whose life history was completely worked out by Thomas in 1883. Habit and Habitat: It is endoparasites. That completes its life cycle in two hosts. Adult F. hepatica is known as sheep liver fluke because it occurs in the liver and the bile passage of sheep. Single adult sheep may have 200 adult fluke in its liver, which may stop the liver function. This effect is known as fascioliasis (Liver rot). F. Hepatica spends some part of life cycle in an intermediate host, like gastropods. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

5. Structure of Fasciola Hepatica: Shape, Size and Colour: F. hepatica has a thin, dorsoventrally flattened, leaf-shaped, elongated and oval body. It measures about 25 to 30 mm in length and 4 to 12 mm in breadth. It is usually pinkish in colour but it appears brownish due to ingested bile of the host. External Morphology: The anterior end of the body is distinguished into a triangular oral cone or head lobe giving it a shouldered appearance. The head lobe, at its tip, bears a somewhat triangular aperture called mouth. There are two muscular suckers an oral sucker at the anterior end encircling the mouth, and a large ventral sucker or acetabulum situated mid-ventrally about 3 to 4 mm behind the oral sucker. The suckers are cup-like muscular organs meant for attachment to the host by vacuum. In addition to mouth aperture, there are two permanent apertures on the body; one situated mid-ventrally in front of the ventral sucker is the common genital aperture or gonopore, and the other is situated at the posterior end of the body called the excretory pore. In addition to these apertures, a temporary opening of Laurer’s canal appears during the breeding season on the dorsal surface just anterior to the middle of the body. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

6. Excretory System of Fasciola Hepatica: The excretory system of Fasciola hepatica is concerned with excretion as well as osmoregulation. It consists of a large number of flame cells or flame bulbs or protonephridia connected with a system of excretory ducts. i ) Flame Cells: The flame cells, supposed to be modified mesenchymal cells, are numerous, irregular in shape bulb-like bodies found distributed in the mesenchyma throughout the body of Fasciola. The flame cells are characteristic, each has a thin elastic wall with pseudopodia-like processes. In living condition, the cilia vibrate like a flickering flame, hence, the name flame cell. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

7. (ii) Excretory Ducts: There is an excretory pore at the posterior end from which arises a longitudinal excretory canal, from this arise four main branches, two dorsal and two ventral. W hich subdivide into numerous small capillaries; the capillaries are continued into the intracellular cavity of flame cells. The longitudinal excretory canal is non-ciliated but the capillaries are lined with cilia. iii) Process of Excretion: The excretory wastes, generally fatty acids and ammonia, are diffused from surrounding mesenchyme into the flame cells and finally collected into their intracellular cavities. The vibrating movement of the cilia causes the flow of wastes from the intracellular cavities of flame cells into the excretory ducts and then into the main excretory canal and finally to the exterior through excretory pore by hydrostatic pressure. Excretory waste → Mesenchyme → Flame cells →Capillaries → Vessels →Trunks →Main longitudinal duct →Excretory pore. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

8. FASCIOLA REPRODUCTIVE SYSTEM Fasciola hepatica is hermaphrodite. The female and male genital ducts open into common chamber called genital atrium. The gonads in these liver flukes are well developed. The genital atrium is situated in the anterior part of the body and it open out through common genital aperture or gonopore. The gonopore is located just in front of the acetabulum. Male reproductive system: Testes: Testes are paired and highly lobed structures Its arranged in the large space in the middle and posterior regions of the body. The epithelial lining of these testes gives rise to sperms. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

9. Vas deferentia: Vas deferentia are the narrow slender ducts arising from the testis. They are two in number and these two side by side anteriorly up to the level of acetabulum. A t the acetabulum they unite and form a pear-shaped seminal vesicle which stores sperms. A narrow twisted tube arising from the seminal vesicle called as ejaculatory duct. The ejaculatory duct extends forward and enters the copulatory organ called cirrus. The cirrus extends up to the genital atrium and opens there as male genital aperture. Genital atrium in turn opens out through a common gonopore. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

10. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana Female reproductive system Ovary: Ovary  is a solitary, highly branched and tubular structure. It lies anterior to the testes. Oviduct: Oviduct  is the gathering of all the branches of the ovary. It is short and narrow. It join the median vitelline duct to form the uterus. Uterus is long and convoluted which extends up to the genital atrium and opens out through female genital aperture. Uterus contains large number of capsules with fertilized eggs. A short muscular copulatory tube called  Laurer’s canal  arises from the oviduct. This canal serves as vagina during copulation.

11. Vitelline glands : Vitelline glands  occur as clusters of follicles along entire length of the body. Follicles on each side are connected by fine ductules and these ductules are finally connected to the vitelline duct. The longitudinal ducts of both sides are connected by a transverse duct. The transverse duct swells up in the center to form yolk reservoir and from this median vitelline duct arises and it joins the oviduct to form the uterus. These vitellaria produce special yolk cells or vitelline gland cells. These cells contain abundant yolk for the nourishment of the embryo. Mehlis’s glands: These are also known as the shell glands. These are the clusters of unicellular glands present at the junction of the oviduct, median vitelline duct and uterus. The secretions of these glands help in lubricating the uterus for smooth passage of eggs and in activating the sperms.