Histological investigation of ovarian maturation stage on European Catfish (Silurus glanis L., 1758) in Anzaly Lagoon in Anzaly Lagoon

The ovarian histological characterization of European Catfish on Anzaly lagoon was investigated. 154 female’s specimen in different size were caught by trap, ovarian were fixed in bouin׳s liquid. Samples were fixed, dehydrated, clarified, embedded and stained by H&E method. The tissues were supplied on 0.5µ size and analyzed by light microscope. The ovaries had six maturity stages which were as follow: Immature, Early Developing, Late Developing, Ripe Ovary, Running Ripe Ovary and Spent. Oocyte diameter was measured for 123 female’s specimen in the 2 to 5 maturity stages. In this study, the mean egg diameter, in stage II of gonad maturation was 1/4 mm and gradually increased in the later stages of development, in the fifth stage of the maturation process the average diameter reached to 2/36 mm and again in the sixth stage decreased the oocyte diameter. Also according the present study the type of gonad in this species under the climatic condition of Guilan Province was found on Group Synchronous and spawning in longer period.