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Purpose: Human papillomavirus (HPV) has been shown to disrupt late-stage implanting embryos. The objectives were (a) to assess the development of early embryos exposed to HPV DNA and (b) to analyze the blastocyst hatching process after HPV exposure. Methods:The study involved exposing two-cell and 4-8-cell mouse embryos to DNA fragments from either HPV type 16, type 18 or DQA1 (control). The embryos were incubated for 120 h and assessed. Results: HPV 16 and 18 inhibited two-cell embryo development. In contrast, delaying the exposure of HPV DNA until the 4-8-cell stage resulted in further embryonic development. There was 25.9% less blastocyst formed with HPV 16 exposure. Additionally, there were 25.9-31.8% more degenerated embryos with HPV 16 exposure. Conclusions:The study demonstrated embryo stage-specific effects of HPV on early development. The results suggested HPV exposure was linked to two-cell embryo demise and delaying the exposure of HPV until later embryo stages permitted embryo development. HPV 16 was shown to decrease blastocyst formation while HPV 18 inhibited the blastocyst hatching process.

This paper postulates that in the ovary, the close association between the cumulus cells and the oocytes permits the fertilizing ability of the oocytes to be determined indirectly through cumulus cell DNA status. The objective was to use a modified comet assay to analyse cumulus cell DNA and relate the data to oocyte fertilization after intracytoplasmic sperm injection (ICSI) procedures. Oocytes were retrieved (n = 15 cases) and free-floating cumulus cells were pooled and smeared on clear glass slides to dry. Meanwhile, the denuded oocytes were injected with spermatozoa and fertilization was assessed, followed by embryo transfer. The fixed cumulus cells were stained in acridine orange, coated with a mini-gel agarose layer, lysed in alkaline buffer and electrophoresis performed. Analyses of fluorescent cell images (n = 449) showed that the tail moment was positively correlated to the percentage of fertilization after ICSI (r = 0.567, P < 0.05). In contrast, there was no correlation between tail moment and number of oocytes retrieved, total ampoules used, endometrial thickness and age of patient. The results suggested that the competence of the oocytes was associated with the cumulus cell DNA status. A unique feature here was the comet assay for archived material with obvious advantages.