On the structure of Raillietina echinobothrida, the tapeworm of domestic fowl


The structure of Raillietina echinobothrida, the gastrointestinal tapeworm of the domestic fowl, Gallus domesticus, was studied using light and scanning electron microscopy. There are already reports on the fine structure of the parasite; however, due to the choice of procedure, many of the resultant information are inadequate, contradicting, and occasionally, erroneous. A slightly modified technique in the microscopic preparations employed in the present study such as the use of formaldehyde as a fixative and tetramethylsilane prior to air drying for SEM, and successive treatments with xylene and clove oil during histological processing provided far more superior methods, and definitely, better results. Unlike in other studies, the scolex was unambiguously a round, distended and bulbous anterior end of the body. The suckers were protruding oval structures, while the apical rostellum was distinctly an invaginated, depressed and hollow structure. The central spaces of both the suckers and rostellum were covered with smooth tegument, made up of ciliary microtriches. The microtriches on the proglottids were arranged in smooth cascades, all directed toward the posterior, and giving the topography of the tegument a uniform velvety appearance. The body cavity was mostly occupied by uteri containing fertilized eggs in a gravid proglottid; and by testes, ovaries, and vitellarium dispersed among the parenchyma in a mature proglottid. The parenchyma notably filled up the remaining pseudocoel of the body. The distinctive characteristics of R. echinobothrida were established to be the double layered rostellum of pick mattock-shaped hooks, a thick short neck and a single egg in each egg capsule.

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