urohypophysis

The urohypophysis, an organ found only in elasmobranch and bony fishes, probably developed independently in each group. The neurosecretory cells comprising the urohypophysis are concentrated at the hind end of the spinal cord, where they are associated with a vascular plexus to form a neurohemal organ.…

…unique neurosecretory neurohemal organ, the urophysis, which is associated with the spinal cord at the base of the tail. Although the functions of this caudal (rear) neurosecretory system are not now understood, it is known to produce two peptides, urotensin I and urotensin II. Urotensin I is chemically related to…