1 Department of Obstetrics and Gynaecology, Llandough Hospital, Penarth CF64 2XX and 2 University Hospital of Wales, Cardiff, UK
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: gamete intra-Fallopian transfer/light/oocytes/ultraviolet radiation
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The effect of visible light on human oocytes is not clear. In animal models, however, the effects of components of the electromagnetic wave spectrum have been studied, with chromosomal and developmental abnormalities being observed in the oocytes of various species (Smith, 1993; Mise and Wakahara, 1994
; Bavister, 1995
; Bradshaw et al., 1995
; Cohen et al., 1997
).
Clinical experience led us to study the effect of different light sources on the pregnancy rates being achieved with GIFT and resulted in a retrospective study of the previous 18 months.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Of the 20 couples started on a cycle of GIFT in the first 6 months of the study, two were cancelled because of poor ovarian response. Eighteen GIFT procedures were performed laparoscopically using a halogen 150 W light source (source 150; Down's Surgical Ltd, Mitcham, Surrey, UK) and no camera.
An endoscopic camera system was then installed (Richard Wolfe 5370CCD®; Endocam, Knittlingen, Germany), together with a xenon 300 W light source (Luxtech Fibre-optics 1900®; Luxtech Corporation, Stourbridge, MA, USA). This system was used for the subsequent 13 GIFT cycles apart from one GIFT which was cancelled during this time because of poor ovarian response.
Eight months later the camera system was sent for repair and following that five GIFT cycles were commenced; one was cancelled and four were performed returning to the old technique using the halogen light source and no camera. Following the last procedure embryological support was withdrawn and GIFT could no longer be performed.
High sensitivity HCG estimation was performed on day 28 and a scan was performed 4 weeks following GIFT procedure. Pregnancies were defined as biochemical, ongoing, ectopic or miscarriage.
The same consultant anaesthetist and gynaecologist performed all procedures and the same embryologist was present for all procedures using similar techniques and culture media.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Using a halogen light source the pregnancy rate was therefore 50% and using a xenon light source the pregnancy rate was 8.3%.
A logistic regression was performed to assess the relationship between the different factors measured and the outcome of pregnant/not pregnant. The factors included in the model were age of the woman, years of infertility, number of oocytes recovered, number of oocytes replaced, washed sperm count, washed sperm motility and the light source (Table I). The only significant predictor in the model was the light source, which had an odds ratio of pregnancy on xenon to halogen of 0.03, controlling for other variables in the model (the 95% confidence intervals for this were 0.0016 and 0.62). All other variables mentioned were not significant. This indicates that there was a significant difference in the odds of pregnancy with the two light sources, with the odds for the xenon source being significantly lower than those for the halogen.
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
The effect of ultraviolet light UVC (254 nm) and UVA (>330 nm) has been studied on bovine oocytes at the germinal vesicle and metaphase II stage. Both UVA and UVC irradiation caused abnormalities of meiosis and production of maturation promoting factor (MPF) at both germinal vesicle and metaphase II stages. This resulted in abnormal parthenogenetic activity, with loss of the female pronucleus being seen after UVC irradiation and an abnormal female pronucleus after UVA irradiation in metaphase II oocytes. Meiotic arrest and abolition of the spindle occurred in germinal vesicle stage oocytes (Bradshaw et al., 1995). Other studies of brief exposure to UV light of bovine secondary oocytes revealed increased membrane lysis and increased methionine uptake, but reduced methionine incorporation into protein and a marked difference in the patterns of protein synthesis (Smith, 1993
). Abnormalities in the development of dorsal axis structures have been reported after UV irradiation of the mature oocytes of Xenopus laevis (Mise and Wakahara, 1994
), and DNA damage in the egg nucleus leading to a failed activation of MPF and prolongation of prophase and metaphase was noted in newt oocytes following UV irradiation (Iwao et al., 1993
).
Experimental evidence (Ashwood-Smith and Edwards, 1996) suggests that whilst the oocyte has the capacity to repair DNA damage due to UV light, X-ray irradiation and mutagenic chemicals at the dictyate (arrested) stage of meiosis, its repair ability is reduced, making it more sensitive, before and after this stage. Oxygen deprivation, either in vitro or in vivo, due to impaired development of the follicular microvasculature, and temperature appear to have a similar capacity to damage the microtubular structure and hence result in chromosomal and DNA damage (Ashwood-Smith and Edwards, 1996
).
Visible light appears to inflict far less damage on oocytes with mouse oocytes exposed to light at 4000 lux for 1, 2, or 4 h showing no differences after IVF in rates of cleavage, implantation and normal offspring compared to controls (Barlow et al., 1992). This finding was supported by work on rabbit unfertilized and pronuclear oocytes exposed to fluorescent light where again no effect was seen on subsequent implantation and development (Bedford and Dobrenis, 1989
).
It would appear therefore that there may be evidence to support the hypothesis that the increased UV light from the xenon light source could have affected the pregnancy rates. Further studies may be indicated on both the effect of UV and infrared emissions, but in the meantime it is suggested that ultraviolet filters could be considered or camera systems incorporating high intensity light sources be avoided when performing GIFT.
![]() |
Acknowledgments |
---|
![]() |
Notes |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Ashwood-Smith, M.J. and Edwards, R.G. (1996) DNA repair by oocytes. Mol. Hum. Reprod., 2, 4651.[Abstract]
Barlow, P., Puissant, F., Van der Zwalmen, P. et al. (1992) In vitro fertilisation, development and implantation after exposure of mature mouse oocytes to visible light. Mol. Reprod. Dev., 33, 297302.[ISI][Medline]
Bavister, B.D. (1995) Culture of preimplantation embryos: facts and artifacts. Hum. Reprod. Update, 1, 91148.[ISI]
Bedford, J.M. and Dobrenis, A. (1989) Light exposure of oocytes and pregnancy rates after their transfer in the rabbit. J. Reprod. Fertil., 85, 477481.[Abstract]
Bradshaw, J., Jung, T., Fulka, J.Jr et al. (1995) UV irradiation of chromosomal DNA and its effect upon MPF and meiosis in mammalian oocytes. Mol. Reprod. Dev., 41, 503512.[ISI][Medline]
Cohen, J., Gilligan, A., Esposito, W. et al. (1997) Ambient air and its potential effects on conception in vitro. Hum. Reprod., 12, 17421749.[Abstract]
Iwao, Y., Sakomoto, N., Takahara, K. et al. (1993) The egg nucleus regulates the behaviour of sperm nuclei as well as cycling of MPF in physiologically polyspermic newt eggs. Dev. Biol., 160, 1527.[ISI][Medline]
Mise, N. and Wakahara, M. (1994) Dorsoventral polarization and formation of dorsal axial structures in Xenopus laevis: analyses using UV irradiation of the full grown oocytes and after fertilisation. Int. J. Dev. Biol., 38, 447453.[ISI][Medline]
Ranieri, M., Beckett, V.A., Marchant, S. et al. (1995) Gamete intra-Fallopian transfer or in-vitro fertilization after failed ovarian stimulation and intrauterine insemination in unexplained infertility? Hum. Reprod., 10, 20232026.[Abstract]
Smith, L.C. (1993) Membrane and intracellular effects of ultraviolet irradiation with Hoechst 33342 on bovine secondary oocytes matured in vitro. J. Reprod. Fertil., 99, 3944.[Abstract]
Submitted on May 13, 1998; accepted on October 14, 1998.