Date of Award
Master of Science
Understanding the fundamental physiological mechanisms underlying ovarian physiology is important for accomplishing ways to diagnose and treat ovulatory dysfunction. With the advancement of assisted reproductive technologies, it became imperative to understand the details of the factors that affect the follicular development, oocyte competence, and embryo production. In primates and large domestic species including women and mares, ovarian follicles grow in a wave-like fashion with waves that can be anovulatory or ovulatory. Although considerable progress has been made in understanding ovarian follicular dynamics, more knowledge needs to be acquired to treat ovulatory problems like luteinized unruptured follicle (LUF) syndrome. Such information can be applied to optimizing treatment outcomes through assisted reproductive technologies that can be of benefit to both humans and animals. Three studies involving five experiments were conducted to improve our understanding on: 1) follicular growth patterns and endocrine profiles of LUFs and dominant follicles of major anovulatory and ovulatory waves in women; 2) physiologic mechanisms underlying luteinized unruptured follicles (LUFs) in mares with the goal of providing a model for human anovulation; and 3) dynamic changes in intrafollicular growth factors and hormones during the dominance and impending ovulation phases in mares. The results from Study 1 indicated that growth and endocrinological differences existed among LUFs, and physiological anovulatory and ovulatory dominant follicles in women. These differences were observed in follicle growth rates, intervals between follicular events, and in systemic concentration of hormones. In Study 2, LUFs were induced in 100% of the mares evaluated using a prostaglandin synthesis inhibitor; differences in intrafollicular prostaglandins, estradiol, growth hormone (GH), cortisol, and PRL were observed. In Study 3, changes in the concentrations of intrafollicular growth factors and hormones such as insulin-like growth factor-1 (IGF-1), inhibin-A, activin-A, VEGF, and PRL were detected during the dominance and impending ovulation phases in mares. The above-mentioned findings will provide the basis to compare the intrafollicular growth factors and hormones of potential LUFs and normal ovulatory follicles in the future. In conclusion, the results from these studies will shed light in the design of future studies on mechanisms of LUF formation and the role of intrafollicular growth factors and hormones in ovulation in women, mares, and perhaps also in other species.
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