Objective: The purpose of this study was to determine if oocytes were capable of taking up exogenous DNA such as human papillomaviral (HPV) DNA and evaluate the zona pellucida as a barrier to the entry of foreign DNA into the oocyte.
Methods: The experiment consisted of four groups of hamster oocytes exposed to HPV DNA fragments: Group A, zona-free oocytes (n = 5); Group B, oocytes with an intact zona pellucida (n = 5); Group C, oocytes fixed in 4% buffered formalin solution for 20 min (n = 5); and Group D, zona-free oocytes (n = 4). Group C oocytes served as an internal control to ensure adequate washing of the oocytes after incubation.
Results: The zona pellucida was not a barrier to foreign DNA molecules. The PCR did not detect L1-HPV and beta-globin gene sequences in the untreated hamster oocyte. Uptake of the smaller DNA fragments such as that amplified from the beta-globin region was independent of active oocyte cell processes.
Conclusion: Oocytes cultured in vitro can passively take up exogenous DNA fragments. The results suggest a possible role of oocytes as vectors for foreign DNA.