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Investigations were carried out on trout larvae (Salmothymus obtrusirostris, Heckel, 1851) age of 10-56 days caught from Vrljika river, Croatia. Larvae were taken every two days from 10 to 50 days and 56 days and were stained with hematoxylin and eosin (HE), Periodic Acid-Shiff reaction, toluidin blue (TB), Alcian blue-specific (pH=2.5) (AB) and alcian blue and alizarin red. Organogenesis of the larvae were analyzed, primarily the development and morphology of muscle tissue, osteological development and development of digestive tract. The number of myomeres in dorsal epaxial musculature on the larvae were measured and it was on 10-18 days 42.17, 20-28 days 50.40, 30-38 days 55.65, 40-48 days 56.92 and 50-56 days 58.90 myomeres. Total length (TL) increased from minimal length of 19.57 mm on 10-28 days to maximal TL 25.80 mm on 50-56 days. Number of verterbres in all investigated groups was 59. There was no sign of ossification in the vertebral column or in the fins and in the head bones. Growth of larval to complete yolk sac absorption takes in the age about 24-26 days when the animals pass through the opening of the mouth. In all investigated of larvae was not skeletal malformations. |
