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Objective: To study and recognizing the morphologic and
microscopic features of spleen as the most important
lymphatic organ and other lymphoid parts affecting on
immune system of Acipenser persicus.
Design: Descriptive study.
Animals: A total number of 10 adult fish freshly prepared from Caspian Sea.
Procedure: After removing the spleen and digestive
canals, they were immediately fixed in ko3AllO formalin
and transported to the laboratory. Routine histological
procedures were made in autotechnicon and the paraffin
sections of 6 micron were stained by Haematoxylin and
Eosin.
Results: Spleen as an elongated organ located on the
middle part of digestive canal and microscopically was
covered by a capsule of connective tissue and an epithelial
layer. Spleen included white and red pulps. There are some
similarities and also some differences between spleen of this species and mammals. A part of immune system is in
the form of diffuse lymphatic tissue throughout the
digestive canal and lymphatic aggregations in lamina
propria and submucosa of proximal and distal intestines
and spiral valves. Generally from proximal intestine to the
posterior parts up to rectum lymph nodules and tissues are
generally increased. Conclusion: Spleen as the biggest and the most important lymphatic organ and microscopically very similar to the
spleen of mammals has many function such as lymphatic
cell production. Besides other lymphoid tissues such as lymph nodules in proximal and distal intestines might
have an important role in immunity with highly lymphatic cell production. J.Fac. Vet.Med. Univ. Tehran. 60,1:37-42,2005.