THE ROLE OF PINEAL GLAND IN SEASONAL CHANGES OF BLOOD ESTRADIOL LEVEL IN IMMATURE AND MATURE CARP FEMALES

Abstract

Effects of pinealectomy (Px) on the blood estradiol (E) level inmature and in mature carp females during the annual cycle were investigated. Significant differences (p<0.01) in the E levels between the Px fish and the control group were found only in mature females during the spring period before the spawning season. These results may indicate that the pineal gland can affect one of the phases of gonad maturation cycles in carp, probably through a stimulating influence of melatonin on E level in the final phase of vitellogenesis.