EN
The aim of this work was to determine the activity of the akrosin inhibitor on the basis of depressing the tripsin activity of polar fox (Alopex lagopus) semen and to follow the changes that affect these properties throughout the whole reproductive season. Additionally, the molecular forms of the inhibitor were electrophoretically separated. The research covered 126 ejaculates obtained manually seven times from 18 polar foxes (at intervals of 10-12 days). The highest inhibitor activity was observed in the seminal plasma from the ejaculates obtained in the first sample, the lowest results were characteristic of the fifth sample. The lowest activity of the akrosin inhibitor, determined on the basis of depressing the tripsin activity, indicates either the weakest protection of the semen proteins along with the whole reproductive system from the influence of the akrosin devoid of damaged acrosomes or the already initiated process of proteolysis.