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''Ancylostoma caninum'' is a species of nematode known as a hookworm, which principally infects the small intestine of dogs. The result of ''A. caninum'' infection ranges from asymptomatic cases to death of the dog; better nourishment, increasing age, prior ''A. caninum'' exposure or vaccination are all linked to improved survival.〔 Other hosts include carnivores such as wolves, foxes and cats with a small number of cases having been reported in humans.〔〔 Warm and moist conditions are important to allow survival of ''A. caninum'' during the free-living stages of its life cycle and for this reason it is largely restricted to temperate, tropical and sub-tropical regions.〔 In parts of the world where these climatic requirements are met such as Sri Lanka, southeast Asia and Malaysia ''A. caninum'' is the main cause of hookworm disease in canines.〔〔 ==Morphology== ''A. caninum'' females are typically long and wide, while the males are smaller at in length and in width.〔〔 On males a (copulatory bursa ) exists which, during copulation, attaches the female via ~0.9 mm long spine-like spicules positioned on three muscular rays.〔〔〔 As with other nematodes, the sperm lack flagella.〔 The copulatory bursa is a unique feature of Strongylida members, thus making it a useful means for identifying members of this suborder; it is also used to distinguish members within the suborder due to differences in bursa appearance between species.〔 The vulva of ''A. caninum'' females is located at the boundary of the second and final thirds of the body.〔 The teeth of ''A. caninum'' are found in the (buccal capsule ) and divided into three sets.〔〔 Two ventral sets form a lower-jaw equivalent, while a further set projects from the dorsal side and loosely equates to an upper-jaw.〔 Each ventral set has three points with those furthest to the sides being the largest.〔 While the ventral sets are prominent, the dorsal set is hidden deeper in the buccal capsule.〔 ''A. caninum'' bends its head end upward (dorsally) which has in the past been noted as a potential source confusion when determining how the hookworm is oriented.〔 If it has recently ingested blood ''A. caninum'' is red in colour, if not it appears grey.〔 ''A. caninum'' has an alimentary canal made up of an esophagus, intestine and rectum – the esophagus is highly muscular reflecting its role in pulling intestinal mucosa into the body when it feeds.〔〔 Esophageal and anal rings of ''A. caninum'' are the source of nerve fibres that extend throughout the body to innervate sensory organs including amphids and phasmids.〔〔 Eggs are laid by the females typically when at the 8-cell stage.〔 Eggs are 38-43 μM in width with thin walls.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ancylostoma caninum」の詳細全文を読む スポンサード リンク
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