On the structure of Ascaridia galli, the roundworm of domestic fowl


Ascaridia galli Schrank is by far the most notorious nematode parasite of birds including poultry fowls in terms of prevalence and pathogenicity. In spite of its immense impact on poultry industry and wildlife management, information on its detail morphological and anatomical structures is scanty. Scanning electron microscopy revealed that the extreme anterior cephalic region is a triangular mouth consisting of three prominent lips. Each lip is lined with fine teeth on the internal rim, and externally studded with eye-like sensory papillae. The body cuticle constituted series of striations called annulations. Annuli are transverse concentric rings and were divided further into parallel subannuli. Female had a simple straight tail with a ventrally located anal opening. The male posterior was curved and pointed, and relatively elaborate having a precloacal sucker in addition to the anus. These posterior openings were surrounded on both sides by a row of minute protrusions called caudal papillae and the lateral caudal alae. The precloacal sucker was surrounded by a sclerotized ring. Light microscopy showed that the cuticle was multilayered and continuous with the hypodermis, which in turn was supported with a thick musculature composed of fibrillar contractile and granular noncontractile protoplasmic portions. The body space, pseudocoel, contained digestive tract and reproductive organs such as testis, vas deferens and seminal vesicle in male, and ovaries, oviducts and uteri in female. The seminal vesicle housed spermatozoa, and the uteri, fertilized eggs. The eggs were elliptical, covered with chitinous shell that enclosed the embryo.

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