Anatomy of finfish and shellfish

Unit 9 - Endocrine system

9.2.8. Ultimobranchial Body
An ultimobranchial body is said to be present in the sharks,holocephalans, and some ray-finned fishes.in some of the teleosts,there is flat discoidal mass lying in the connective tissue between the floor of the oesophagous and the sinus venosus. This organ secretes calcitonin (lowers serum calcium levels) that acts with hypocalcin (secreted by the corpuscles of Stannius) to regulate calcium metabolism.