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Cytological state of gonads and hormonal status was studied in juvenile (15-month-old) Black Sea trout Salmo trutta labrax of the two phenotypic forms (resident and migratory). The differences in the rates of hametogenesis in the compared forms were revealed. It is shown that the spermatogenesis in the resident form is more intensive; on the other hand, the(More)
The diurnal dynamics of the content of thyroid and sex steroid hormones is investigated in the blood of the resident form of Black Sea trout in summer. The maximums and minimums of concentration of the investigated hormones do not coincide over 24 h, except for the decrease in the level of T3 and testosterone before dawn. The dynamics of the investigated(More)
The rheoreaction of juvenile rainbow trout (aged 2 months) was studied 30–40 days after a single injection of surfagon (synthetic analogue of gonadotropin-releasing hormone). Individuals subjected to surfagon preferred to move against the water current both in normal and migratory state, while control (not injected) individuals preferred to move downstream.(More)
The content of thyroid and sex steroid hormones is determined in fish-farm juveniles of Black Sea trout, 5.5 months old, from the bottom and pelagic spatial groups differing in the probability of future selection of the resident or anadromous life strategies, respectively. Differences in the concentration of the aforementioned hormones are found in(More)
Cytological state of the gonads and hormonal state of hatchery Black Sea trout before differentiation into resident and anadromous forms (parr) at an age of 15 months have been examined. It has been shown that the hormonal changes associated with the choice of life strategy in the Black Sea trout females and males are pronounced to different degrees. As(More)
Changes in the morphology of gonads under the effect of methyltestosterone in juveniles of triploid rainbow trout Oncorhynchus mykiss incubated and cultivated in a trout farm under climatic conditions of South Vietnam have been studied. It was shown that the effect of the androgenic hormone intensifies the formation and development of testes in triploid(More)
The effect of methyltestosterone given with feed during one and two months on the state of gonads, the level of thyroid, and sex steroid hormones in blood and on rheoreaction is studied in juvenile rainbow trout Parasalmo mykiss (=Oncorhynchus mykiss) raised under unfavorable conditions (tropics, Vietnam). In comparison with the control, in the experimental(More)
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