Abstract
The corpuscles of Stannius (CS) are numerous spherical- bodies like glands located in the middle and caudal part of the dorsal region of the mesonephric (trunk) kidney kidney in tilapia, Oreachromis niloticus. In grouper, Epinephelus tuvina, CS are a single pair of corpuscles located on the dorso- caudal part of the trunk kidney and associated with the distal portion of the tubular nephrons. Histologically, each CS was encapsulated in highly vascularised connective tissue and divided into lobes and lobules of cells of variable appearance. Ultrastructural examination of the glands, demonstrated two structurally different types of gland cells in tilapia and grouper displayed cytological features typical of protein producing cells. The dark ( Type I) and light (Type II) cells are numerically different and differ in size and amount of secretory granules and amount of rough endoplasmic reticulum. The secretory granules appear to originate at the Golgi cisternae and exocytosis into intercellular spaces between cells and to blood vessels are also evident in the two cell types. CS of salt water grouper is more active than in fresh water tilapia. CS are highly innervated by unmyelinated nerve fibers mainly in grouper suggesting a functional link between neurotransmitters and CS cells.