Anatomy of finfish and shellfish

Unit 9 - Endocrine system

9.2.3. Chromaffin tissue
Adrenal tissue are present in all vertebrates from cyclostomata to mammals but profound differences are encounted in the arrangement of the functional components i.e.,steroid producing cells and catecholamine producing cells.in Elasmobranches the stereo genetic tissue is composed into several well form bodies lying between the caudal ends are kidneys.these are interregnal glands.paired aggregation of chromaffin pairs are present between kidneys.the two components of the adrenal are typically separated through small cells of chromaffin cells and have been described in the interregnal gland of the ray.Great variation is found among actinopterygian fishes(teleost) with respect to the condensation and dispersion of adrenal tissue.these are generally located within or just anterior to the cephalic kidney and occur around the post cordinal veins and their branches.