Browsing by Author "Raubenheimer, Kara"

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    The impact of oocyte meiotic spindle and automated zona pellucida score and sperm chromatin packaging on fertilization and pregnancy for assisted reproduction techniques
    (Stellenbosch : Stellenbosch University, 2016-03) Raubenheimer, Kara; Du Plessis, S. S.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Medical Physiology.
    ENGLISH ABSTRACT: Non-invasive selection of developmentally competent human oocytes may provide information on the true fertilization potential of the spermatozoon in the absence of oocyte limitations. The objective was to measure 856 oocyte’s competence by assessing oocyte metaphase 2 (M2) maturity, zona pellucida score (ZS) and presence of the meiotic spindle (SPp) using birefringent imaging software. ICSI was performed and fertilization (n=90 patients) and pregnancy rates (n=89) were measured and compared to the oocyte competence and sperm DNA chromatin via Chromomycin A3 (CMA3) (n=89). Fisher’s exact and odds ratio’s (OR) were used to determine effect. In total, 856 oocytes were harvested of which 568 (66%) were M2 stage of development. SPp oocytes were (384/730) 52.60%, OR was performed on the SP to determine its relevance to fertilization, its presence in the oocyte prior to ICSI, resulted in fertilization 1.5:1 times more than when it was absent, p=0.01. SPp embryos selected for embryo transfer resulted in a 65% expanded blastocyst rate, full blastocyst rate of 58% and early blastocyst rate of 54%. A negative development competence on day 5 was also correlated to absence of meiotic spindle (SPa) prior to ICSI with 56% of day 5 embryos transferred reaching only the compacted morula stage; while 50% of SPa embryos reached the morula stage at time of embryo transfer on day 5. Although there were no statistical differences between the pregnancy rates of SPp and SPa embryos, there were slight tendencies for better embryo quality. The SPp had a pregnancy rate (PR) of 40.91% (36/88). Random effects logistic regression OR performed on 768 oocytes from 90 patients indicated pregnancy to succeed 1.4:1 when SPp (p=0.89). The mean average automated ZS was 18.96 μm (95% CI: 15.75; 22.16; n=625 positive ZS from 90 patients). The ZS revealed a GLS linear regression with p=0.04 to fertilize when the ZS was 19.20 μm (16.60; 21.79). There was no statistical difference between ZS of the pregnant and non-pregnant groups. The main objective was to prove that when oocyte quality is optimized, that fertilization rates and by implication, pregnancy rates would be improved. If not, failure to fertilize or implant would most probably be due to decreased spermatozoa capacity to fertilize possibly due to damaged chromatin packaging. The chromatin packaging (CMA3) of the study population was 74% semen samples with >40% immature DNA. The OR for CMA3 underlines the hypothesis, that when oocyte competence for fertilization is controlled to a degree, the success or failure of treatment can be indicated by the CMA3 value. In this instance, the OR is highly predictive for success with pregnancy when ICSI is performed on CMA3 values that are immature (≥41%). Logistic regression calculated the OR for immature DNA (CMA3≥41%) to predict pregnancy to be likely with odds of 1.6:1, p=0.39. Hypothesis OR: If ICSI is performed on an oocyte with: M2 and SPp, and this embryo develops to day 5 for embryo transfer, the odds of pregnancy, if working with a semen sample with >40% immature DNA, would be 1.9: 1.