| Abstract: | Daily changes of gonadotropin (GtH2) blood levels of immature and mature carp females were investigated in four seasons during the year: spring, summer (spawning period) and in autumn and winter (“resting” period). GtH2 levels were measured using ELISA method. The maturity stage of oocytes was determined histologically and on the base of germinal vesicle position in the oocyte. It appeared shown that GtH2 levels changed daily during the year in the range of 3.56 to 6.61 ng/ml, regardless of the state of ovarian maturity. Cosinor analysis and ellipse of errors revealed the presence of a circadian rhythm in GtH2 levels only in mature females during the reproduction period (L:D=16:8, water temp. 20 to 22°C). |
