Aortic Arches In Vertebrate Analysis

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DEFINITION: Aortic arches are also called as pharyngeal arteries. They are vascular structures that emerge from the ventricle of the heart. There are 6 pairs of these arches in embryonic stages which give rise to several major arteries later. They arise from the aortic sac and are present on the ventral and dorsal aorta.
As discussed earlier that there are 6 pairs of aortic arches present in embryonic stages giving rise to several arteries are as follows:
Arch 1st and 2nd: The first and second arches lost or degenerate soon, but the ruminant of first arch gives rise to maxillary artery while the second arch forms stapedial artery.
Arch 3rd: The third arch is also
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Branchiostoma (amphioxus) has about 60 pairs of aortic arches, but Petromyzon has only 7 pairs while Myxine has 6 pairs of aortic arches. Cyclostomes which are a primitive vertebrate include 6-15 arches on their ventral and dorsal carotid arteries. They primarily have 6 pairs of arches. During later development the first arch either lost or degenerate.
AORTIC ARCHES IN FISH: In fish the numbers of aortic arches are varying in different categories of fish. Class Pisces is divided into many categories such as jawed fish, bony fish, and lung fish. The changes from elasmobranchs to lung fish i-e the evolution of the pulmonary circulation also change the circulatory system.
Elasmobranchs: Elasmobranchs a primitive fish and Heptanchus contain 7 pairs of aortic arches. But Selachins has 6 pairs of aortic arches. In Scoliodon (sharks) only 5 pairs of aortic arches are present because the first pair is degenerated or develops into non functional gills. The progressive reduction of aortic arches in different species was observed.
Bony fish and Chondrichthyes: The bony fish have single systemic circuit. Bony fishes are also called as telosts. Chondrichthyes have only five pairs of aortic arches because the first pair is lost. While in bony fishes the first and second pairs of arches are lost or

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