THE SPLEEN OF MUSTELUS-SCHMITTI (CHONDRICHTHYES, TRIAKIDAE) - A LIGHTAND ELECTRON-MICROSCOPIC STUDY

The spleen of Mustelus schmitti is described, being an elongated organ running dorsally along the stomach and surrounded by a thin capsule w ithout muscular tissue. The classical division between red and white p ulps was evident, with a marginal sinus surrounding the latter. Numero us ellipsoids were located in the red pulp, inside nodular-like struct ures, or in the marginal sinus. Two types of reticular cells were appa rent as well as macrophages and melanomacrophages. Hemopoiesis was pre sent through immature and mature cells of the erythroid and thrombocyt oid lineages, but no evidence of granulopoiesis was found. Comparisons among Mustelus species and between chondrichthyan and mammalian splee ns are made.