Morphological, Histological and Ultrastructural Evidences of the Stannius Corpuscles in Fresh Water Teleost (Oreochromis niloticus) and Marine Teleost (Epinephilus tuvina)

Morphological, histological and ultrastructural features of the Stannius corpuscles (Stc) in fresh water teleost Oreochromis nilot- icus, and marine teleost, Epinephilus tuvina were studied. In O. niloti- cus, the Stc were numerous paired and randomly scattered throughout the trunk kidney as white corpuscles, with the increase in fish size they became concentrated at the dorso-caudal part of the kidney. In E. tuvina this gland was observed to be represented only by large pair of corpuscles which were always associated with and often connected to the distal portion of the tubular nephrons. In small fish the Stc consisted of undifferentiated cellular mass attached to the posterior part of the kidney tubules. They became encapsulated and divided into lobules of secretory cells with increase in fish size. Ultrastructure study of the gland demonstrated two main types (Type 1 and Type 2) of secretory cells in the two teleosts with secretory granules. Type 1 cell predominating in the gland with large granules, numerous free ribosomes, lysosomes and ribosomal endoplasmic reticulum. Type 2 cell with small secretory granules, extensive arrays of smooth endoplasmic reticulum and ribosomal endoplasmic reticulum. Abundant ribosomal endoplasmic reticulum and well developed Golgi suggested the gland role in protein synthesis. It is important to 59 JKAU: Mar. Sci., Vol. 17, pp: 59-77 (2006 A.D. / 1427 A.H.) 60 Osama A.H. AbuZinadah et al. mention that another non secretory dark cell type was demonstrated in the Stc of E. tuvina characterized by cytoplasmic processes penetrate between the main cells, this dark cell may represent a supporting cell. Cells of Stc were innervated by unmyelinated nerve fibers.