عنوان مقاله [English]
In this study, biopsy was carried out on the gonads of Huso huso having 3 & 4 years old, reared in concrete ponds of Shahid Rajaii hatchery of Sari (50 species) and Shahid Marjani hatchery in Ag-Ghala (25 species). After biometry & recording of data, biopsy of gonads performed. All of the tissue sections stained by hematoxylin & Eosin, then specimens prepared and studied under light microscope connected to a camera and monitor. In female Huso huso of Shahid Marjani hatchery the mean diameter of oocytes were 385.3±73.6, 234.1±59.4 and 36±24.3 µm in stages III, II and I and the mean diameter of nucleus was 80.7±27.8, 63.8±10.8 and 14.5±10.5 µm in stages III, II and I, respectively that showed significant differences (P<0.05).The mean diameter of nucleus in stage III is higher compared to other two stages (P<0.05). In Shahid Rajaii hatchery (Sari), the mean diameter of oocytes in female Huso huso of 3 years old were 381.1±82.1 in stage III, 219.4±54.7 in stage II and 27.3±38.4 µm in stage I, which shows significant differences (P<0.05). Moreover, the mean diameter of nucleus was 75±50.4, 45.7±17.7 and 3.9±0.7 µm in stages III, II and I, respectively. Also, in four years old Huso huso, the mean diameter of oocytes in stage III were 186.1±36.2 µm which was higher than stage II, 120.1±43.4 µm. In addition, the mean diameter of nucleus in stage III of sexual maturity was 55.1±10.9 µm compared to stage II, 44.7±13.9 µm which indicates significant differences (P<0.05). The results showed that the age of examined fishes have not role on the size changes in oocytes and for a species, the size of female oocytes could be in an specific range for each stage of sexual maturity. Statistical analysis shows no significant differences in similar stages of sexual maturity in the fishes of these two hatcheries, too.