An evolution of IVF lab methods and biological observations in human clinical embryology

  • James S. Meriano

Student thesis: Doctoral Thesis

Abstract

Purpose:
The purpose of this study is to explore the evolution of some of the methods, technical tools and observations in the field of clinical embryology and more specifically, intracytoplasmic sperm injection. The inclusion of 16 published studies exploring the areas of ovarian stimulation, sperm quality and oocyte and embryo quality illustrates my modest contributions to these areas.

Materials and Methods:
This study comprises sixteen peer reviewed journal articles from my career work in a clinical embryology lab always striving to better the chances of patients of different diagnostic variabilities to achieve their goal. Research includes:
1. Observations and modification in stimulation protocols, that give patient best chance of
retrieving healthy and competent oocytes.
2. Sperm specimen observations and techniques.
3. Observations in oocyte and embryo morphologies that help the embryologist identify the
most competent oocytes and select best embryos for fresh and frozen transfer.

Results:
Ovarian Stimulation: We found that a long stimulation protocol with gonadotropin releasing hormone agonists and exogenous follicle stimulating hormone were important for the stimulation of oocytes that were mature and of competent quality for our intracytoplasmic sperm injection program. Purified follicle stimulating hormone was comparable to human menopausal gonadotropin at the time, as far as maturation, fertilization and pregnancy rates. The use of aromatase inhibitors for low responder and normal responders showed an increase of retrieved oocytes and increased blastocyst development. Lower estradiol levels lead to lower risk of ovarian hyperstimulation syndrome in these patients.
Sperm quality: Early on, we identified an assay that helped us indicate the use of intracytoplasmic sperm injection in patients with normal sperm parameters but risked failed fertilization with invitro fertilization. Epididymal sperm, was found to be equally useful fresh or frozen, however, we encountered high proportions of non-motile sperm from frozen epididymal samples. Our use of the hypo-osmotic swelling test helped us identify vital sperm without damaging them so that they could be used for injection with better fertilization and pregnancy outcomes than if selecting non-motile sperm with no aid. Deoxyribonucleic acid fragmentation in sperm, was identified as an important measure for infertile male patients. We observed a negative correlation between deoxyribonucleic acid fragmentation, fertilization and sperm morphology. This parameter if elevated, gave lower blastocyst rate and higher miscarriage. We also determined that high deoxyribonucleic acid fragmentation in sperm was more likely to give a higher percentage of aneuploid embryos as evidenced by higher chance of multinucleation in embryos.
Oocyte and embryo quality: Oocyte cytoplasmic quality was observed as intracytoplasmic sperm injection was introduced and central organelle clusters were determined to affect intracytoplasmic sperm injection cycles negatively whether dysmorphism was repetitive from one cycle to the next or not. We studied and identified three multinucleation phenotypes in embryos and characterized different outcomes for these phenotypes and showed that they varied in the level of euploid embryos that developed. We also showed that embryo development rate did not always mean absolute embryo arrest. We showed that it was useful to culture embryos to day six if slow on day five to give patient the possibility of more utilizable embryos. Our modification in the embryo thaw protocol also allowed us to increase pregnancy rates in frozen embryo transfer cycles as well as give patients possibility of more useable embryos. Conclusions: We showed modest advancement in certain areas of clinical embryology that allowed patients better chances of pregnancy. Further research is required in some areas as the advancement of this field progresses.
Date of Award2019
Original languageEnglish
Awarding Institution
  • University of Portsmouth

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