Anatomy of finfish and shellfish

Unit 9 - Endocrine system

9.2.2. Thyroid gland
In elasmobranchs,thyroid is an eucapsulated organ usually located near the point where the afferent branchial arteries leave the ventral aorta. the thyroid is typically an unpaired organ lying below the pharynx. In teleosts the thyroid follicles are scatterd along the ventral aorta.thyroid follicles are often found in the head kidneys of the platy fish (platypolcitus).tyhe number increasing with the age.in a few teleosts such as ‘Bermuda’ Parrot fish, the follicles are arranged to form a compact unpaired gland.