The evaluation referred to polymorphism of heterosomes and autosomes and it was based on measuring their areas in the Polish Landrace and Polish Large White breed sows. The average surface area of sex chromosomes in the researched Polish Landrace breed sows amounted to 7.48 μm2, with the range of values between 6.98 μm2 and 8.13 μm2, while for the Polish Large White sows it amounted to 8.01 μm2, between 6.61 μm2 and 10.89 μm2 respectively. The average surface area of autosomes in the researched Polish Landrace sows amounted to 143.77 μm2, while for
the Polish Large White sows it amounted to 150.01 μm2. In both analyzed breed groups the variability within sex chromosomes was found to be larger than that of autosomes. The variability rate of the surface area of sex chromosome chromatids in a group of the Polish Landrace breed sows amounted to 5.27%, whereas for the Polish Large White breed sows it amounted to 12.06%. The variability of the autosomal chromosome surface areas amounted to 4.92%
and 7.12% respectively.
