W.B.C.S. Main 2018 Question Answer – Zoology – Aortic Arches of Teleost.

WBCS  ২০১৮ মেইনস   প্রশ্নের উত্তর  – প্রাণিবিদ্যা – টেলিওস্টের অর্টিক তোরণ।

Teleosts

In teleosts there are four pairs of aortic arches. First pair (mandibular) and second pair (hyoidean) are lost, only four pairs (third to sixth) persist as branchial arteries . Four pairs afferent branchial arteries arise from the ventral aorta.Continue Reading W.B.C.S. Main 2018 Question Answer – Zoology – Aortic Arches of Teleost.

They supply deoxygenated blood to the gills for aeration. The ventral aorta bifurcates anteriorly to form the first pair of afferent branchial arteries. In sturgeon (Acipenser) and Amia each afferent branchial arch bifurcates as in elasmobranchs.

Generally there are five pairs of aortic arches in elasmobranchs but in some cases there is a variation. In Hexanchus there are six pairs of aortic arches. In Heptranchias there are seven pairs. In elasmobranchs  the first pair of aortic arches (mandibular) disappear. Second to sixth pair of aortic arches (II-VI) persist as branchial arteries. Each aortic arch is divided into afferent and efferent branchial arteries.

Five pairs afferent arteries arise from ventral aorta and supply deoxygenated blood to the respective gills. The ventral aorta divides into two branches, called innominate arteries which again bifurcate into the first and second afferent branchial arteries. From the gills the oxygenated blood is collected by efferent branchial arteries.

In elasmobranchs there are nine pair’s efferent branchial arteries of which the first eight arteries form a series of four complete loops but ninth efferent branchial artery collects blood from the demi- branch of the fifth gill pouch.

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