histological and morphological study of caspian kutum eggs and embryo developmental stages (rutilus frissi kutum kamensky, 1901)

in fish propagation and aquaculture industry, egg incubation period up to hatching is the most critical time. there is scarce information about events happening during this period for caspian kutum, which is a very economically important endemic fish in the caspian sea. morphological and histologial developmental changes of caspian kutum eggs and embryo up to hatching were investigated. developing eggs from incubator was cleared through the exposure of acetic acid (1-2%) to study the morphological and histological observation for tissue changes. early results have shown the cells divisions, archenteron formation and gaustrolation in second day which result in formation of 3 germinal layers including ectoderm, mesoderm and endoderm. histological and morphological studies followed blastoderm extending or epibolic expansions which result in notochord and neural plate formation. after that organization started along with neural formation stage and continued till hatching time. consequently, according to our results, two stages before fertilization and 19 stages after that has been distinguished. eggs were eyed in fifth day after fertilization and larvae hatched finally as usual in seventh days in 18c.