[Functional characteristics of the adrenals in the ontogeny of male water voles Arvicola terrestris with various fur colorings].

Studies have been made of the effect of colour mutations on the adrenal function in growing male voles. In postnatal life, the level of 11-oxycorticosteroids in the blood exhibited similar changes in brown (wild phenotype) and black (mutant) voles. The highest level was found in 1-2-month animals; a decrease took place to the 6th month which was followed by a secondary increase at the age of 8 months. Corticosteron production in vitro is the highest in brown males 5-month. In black voles, after 2 months the production remains unchanged, being rather high. In 5-, 6- and 8-month voles, corticosteron production in vitro increased, but not decreased after prior incubation. In mutant voles, the adrenals are more sensitive to stimulating effect of ACTH (5 units per 1 g of the adrenals) and inhibitory effect of estradiol (40 ng/100 mg) in vitro.