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In this article we will discuss about the morphology of lung fluke (Paragonimus Westermani).
Adult lung fluke is thick, fleshy, oval in shape, reddish brown in colour, about 8-12 mm long and 4-6 mm in diameter. General plan organisation is more or less the same as that of Fasciola. Its anterior end is slightly broader than the posterior end. The cuticle is clothed with minute simple or toothed spines.
The oral sucker is situated anteriorly in the pharyngeal region and the ventral sucker is near about the middle of the body in between the forked intestine. The excretory vesicle is large and extends from the posterior extremity to the anterior region, dividing the body into two equal halves. This vesicle opens at the posterior extremity by an aperture—the excretory pore. The two blind intestinal caeca are un-branched and extend up to the caudal region. The common genital atrium is housed in the ventral region in between oral and ventral sucker (Fig. 9.2).
Male genital system consists of two testes in the posterior region of the body, two vasa-efferentia and one vas-deferens. The vas deferens is dilated into a seminal vesicle followed by a constriction— the ejaculatory duct, before opening into the genital atrium.
The terminal part of vas deferens is modified into a muscular cirrus which serves as the organ of copulation. The seminal vesicle, cirrus and the prostate gland which are associated with male genital system are enclosed in a pouch—the cirrus sac.
Female genital system comprises of a single ovary which lies in front of the testis and its duct, two vitellaria (yolk glands) and their ducts on either side, a vestigeal vagina (Laurer’s canal), seminal receptacle, uterus, ootype and Mehli’s gland.
Eggs:
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The fertilized eggs are golden brown in colour, oval in shape and consists of flattened opercula. The eggs measure 80-118 μm by 48-60 μm and each egg comprises of an un-segmented ovum surrounded by yolk cells.
