ABERRANT KARYOTYPE OF AN EXPERIMENTAL RABBIT (ORYCTOLAGUS-CUNICULUS, LINNAEUS, 1758) WITH A HETEROZYGOUS 1ST AUTOSOMAL PAIR

Histological and cytogenetic analysis was applied to a male from a bre eding stock of experimental rabbits (Oryctolagus cuniculus). The rabbi t originated from the breeding farm of experimental animals at the Fac ulty of Veterinary Sciences in Ljubljana. It was 6 months old, and wei ghed 2.5 to 3 kg. Reduced fertility was evident from the small number of mated females which, conceived frequent premature termination of gr avidity, and reduced vitality of offspiring. The karyotype analysis sh owed an unusually large chromosome in the first pair of autosomes. It was assumed to arise as a consequence of the amplification of some chr omosomal segments, possibly due to an increase in the concentration of food additives in the food consumed. Reduced fertility was interprete d to be the consequence of impaired spermatogenesis, irregular chromos omal segregation during meiosis, and the production of imbalanced game tes.