In light microscopy the tegument appears as a non-cellular homogeneous layer of about 7-16 µm thick. Fasciola hepatica, in addition to sheep, also infects other vertebrates like goat, deer, horse, dog, ass, ox and occasionally man. One pole of the egg shell bears a small lid or operculum for the exit of the future larva. Scanning electron micrographs show that the eggshell of the digenetic trematode, Cryptocotyle lingua, is a concavo-convex ellipsoid with a longitudinal ridge-like demarcation extending along the convex, but not the concave surface. Digestive System of Fasciola : i. Internal Morphology: The architecture of the body wall of F. Observations have been made on the hatching behaviour of the larva of the monogenean Entobdella soleae and on the effects of various enzymes on the opercular cement of the egg.
We suggest that stool examination for eggs is not a reliable method and that both serological testing and extraction of live parasites form bile ducts are very reliable methods for the diagnosis of fascioliasis. In the alimentary canal of a sheep, the cyst wall is digested and a young fluke emerges and bores through the wall of the intestine to enter the body of the host. . From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world. The genital aperture or gonopore is situated on the anterior side of the ventral side. Excretory System: Excretory system is a branching system of vessels, the water vessels that ramify mouth throughout the body.
Its mouth is situated anteriorly and the muscular pharynx serves for sucking the nutrients from the host body. Since it lives in an environment which is devoid of oxygen, hence, anaerobic mode of respiration occurs; respiratory organs are completely wanting. Amino acid analysis demonstrated a marked preponderance of aromatic and heterocyclic acids and it has been suggested that these groups act as cross-linking agents in the shell protein. In consequence there has been a conflict in interpretation Stephenson, 1947, Yosufzai, 1953 and the purpose of this paper has been to attempt some clarification. The changes of the membrane resistance are interpreted as probably caused by alterations in the effective pore size in the plasma membrane. The miracidium swims actively in water or moves on damp herbage and can survive only if it reaches an amphibian snail, the other host, approximately within eight hours-time. So, the adaptive features of Fasciola hepatica can be discussed in the following two headings: A.
The mor-phometry of the eggs is in accordance to those measures presented in previous studies. From each redia 14-20 cercariae are produced. The mode of stabilization of the egg-shell protein of Fasciola hepatica has been studied. It develops a temporary opening on the dorsal body surface during breeding season. Since it feeds on pre-digested and digested substances of the host body, hence, its alimentary canal is not well developed and digestive glands are not found. I should like to thank Professor T. This gland is particularly well developed in the liver fluke, F.
From the ovary oviduct arises which proceeds towards the centre of the body. Groups of unicellular shell glands or accessory female glands, opening by small ducts into the oviduct, are present around the junction. The protein is rich in sulfur-containing amino acids. In all treatments, hatching uniformly began at 13 days and was nearly evenly spread over the next 3 weeks. The eggshells contain keratin and are stabilized by disulphide linkages. The cirrus or penis, seminal vesicle and prostatic glands are surrounded in a common cirrus sheath or cirrus sac.
This acidification is probably responsible for morphological alterations which are notably disturbing in electron microscopy. From the anterior region of the main canal four large canals are given off, each of which branches repeatedly. The resulting offspring are, however, morphologically indistinguishable. The keratin precursor is a rodlet formed by the rolling of a sheet into a scroll and all stages of this process can be recognised in the synthesising cells in the early cercaria. Large numbers of oncomiracidia up to 300 can be packed, in membranous sacs, within the storage capacity of the uterus; direct transfer of nutrients from parent to offspring enables resources to be supplied over an extended period; and infective larvae can be maintained in readiness for an unpredictable opportunity for transmission. This simple life cycle has sufficient evolutionary plasticity to enable monogeneans to adapt to fishes living in a range of marine and freshwater habitats and with strikingly different ways of life, such as bottom-living flat-fishes and fast-moving pelagic species. No consistent and significant membrane potential was measured.
The by-products produced by worms are very toxic and cause anaemia, diarrhoea, eosinophilia etc. The protein is rich in sulfur-containing amino acids. The common genital aperture is situated on the mid-ventral line, just anterior to the ventral sucker. The high energy costs of egg-shell production in many helminths suggests that this structure plays an important role in their biology. In these respects the egg shells of the monogenetic trematodes strongly resemble the egg shell of Fasciola hepatica. It shows backwardly directed spines.
The flame cells open to the exterior by two separate excretory pores or nephridiopores situated laterally in the posterior half of the body. Adela; Perez-Crespo, Ignacio; Periago, M. Tyrosine was present in vitelline cells and immature egg-shell indicating that the proteins involved in quinone-tanning were tyrosine rich and tyrosyl residues are modified to form dityrosine in mature egg-shell. The quality of fixation can be materially improved by buffering the OsO 4 solutions at pH 7. The oesophagus connects the intestine, which immediately divides into right and left caecum; running up to the posterior end and terminates blindly. It was expressed in Escherichia coli as a beta-galactosidase fusion protein, which was purified and used to produce polyclonal antibodies.
Because of its relatively large size and economic importance, it has been the subject of many scientific investigations and may be the best-known of any trematode species. All the three layers were non-refractile during early stages of their formation, and become refringent subsequently. An excretory duct originates from the bladder, travels through the tail and bifurcates to open out through a pair of nephridiopores. They cause serious loss of human life and domestic animals. The metacercaria, encysted on vegetation, may live for as long as a year at low temperature, or for as short time as two or three weeks at 25 degree C.
These observations are discussed in relation to the following 1 survival of the eggs during embryonic development, 2 hatching, 3 the 'hinge' often connecting the operculum to the empty egg-shell, 4 the rapid hatching that occurs in some other monogeneans. Small nerves are given out anteriorly from the ganglia. The mouth leads into a small funnel-shaped buccal cavity. The rediae larvae pass out of the sporocyst by rupture of its body wall into the snail tissues with the aid of the muscular collar and ventral processes, then the rediae migrate to the liver of the snail. The lowest layer of the cuticle forms a delicate basement membrane.