EN
One of the methods of functional assessment of semen is the zona free ova test of an egg cell devoid of zona pellucida, as a result of treating it with trypsyne. This test facilitates checking the interactions between a spermatozoon and an egg cell and determining the fertilization potential of spermatozoa. The material used for the study was sperm collected by using the massage method from 18 polar foxes. Next, oocytes devoid of zona pellucida were introduced into the breeding medium and incubated together with the spermatozoa. Percolls gradient (Pharmacia, Uppsala Sweden) was used in order to separate the spermatozoa. The number of oocytes having both pronuclei (male and female) was determined, and these were used as the basic indicator of proper insemination. The study also took into account the number of oocytes which indicated so-called parthenogenic development (1 pronucleus) as well as those which underwent polyspermic insemination (3 or more pronuclei). The fertility (covering effectiveness) and profligacy of the investigated specimens was determined in order to assess the reproductive efficacy of male specimens on the basis of the number of covered female specimens, the number of whelped female specimens and the number of puppies. The investigated population was characterized by high breeding effectiveness which is supported by studies showing the high fertilization percentage of hamster oocytes in the zona free ova test (67.1%) and their breeding results (fertility 91.02%, profligacy 9.28). The results of the study indicate the utility of the zona free ova test in assessing fertilization capacity of spermatozoa and semen fertility in polar foxes.