Levels of some ovarian hormones in the pre- and post spawning periods of Chaicalbumus tarichi Pallas, 1811, and the postovulatory structure of follicles

The structure of postovulatory follicles and the levels of ovarian 11-dehydrocorticosterone (11-DHC), estradiol-17 beta (E-2), 17 alpha-hydroxyprogesterone (17 alpha-OH-P), and progesterone (P), before and after spawning, were studied in Chalcalburnus tarichi. It was observed that postovulatory follicles are characterized by a highly vascular thecal layer and hypertrophied granulosa cells containing dense smooth endoplasmic reticulum, many large mitochondria with tubular cristae, and lipid droplets. Ovary 11-DHC level was low in the pre- and post-spawning periods (38.3 +/- 4.9-22.3 +/- 2.6 ng/ml). The level of E-2 was 216.8 +/- 31.1 ng/ml before spawning. This hormone declined on the 1(st) and 5(th) day after spawning and increased again to the level of 216.8 +/- 6.7 ng/ml on the 10(th) day; however, the E-2 level decreased significantly on the 15(th) day (61.5 +/- 17.8 ng/ml) (P < 0.01). The 17 alpha-OH-P level was low (84.5 +/- 49.4 ng/ml) before spawning and reached a peak (295.7 +/- 52.5 ng/ml) on the 10(th) postspawning day, but a slight decline was observed on the 15(th) day (190 +/- 21.5 ng/ml) (P > 0.01). The P level was low (23.4 +/- 18.3 ng/ml) before spawning. Its level began to increase after spawning and reached a peak on the 10(th) postspawning day (200.7 +/- 29.1 ng/ml) (P < 0.01), but declined significantly on the 15(th) day (63.2 +/- 19.5 ng/ml) (P < 0.01). The results obtained from this study indicate that: a) In the postovulatory follicles, the granulosa cells produce steroids; b) 11-DHC has no effect before or after spawning; c) E-2 induces spawning; d) 17 alpha-OH-P and P have an effect after spawning. It can be concluded that the apoptotic cells in postovulatory follicles increased on the 1 5th day, at which time E, and P hormones were at their lowest levels after spawning in C. tarichi.