Date of Award

January 2016

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Oliver R. Oakley

Second Advisor

Marcia M. Pierce

Third Advisor

Lindsay E. Calderon

Abstract

Ovulation is a recurring biological process that involves inflammatory reactions that degrade and restructure tissue. It requires the chemotaxis of leukocytes to the ovary to help regulate and promote these events. Hormonal signals and chemokines that are released during the peri-ovulatory period initiate the release of specific leukocyte populations, possibly from the spleen, that infiltrate the ovary and facilitate the release of oocytes from ovarian follicles. These studies utilized a super-ovulation protocol to initiate ovulation in immature balb/c and cd1 mice. Ovaries were collected at several times post human chorionic gonadotropin (hCG) injection and analyzed by multi-color flow cytometry. Oviducts were collected from mice 20 hours after hCG administration and cumulous oocyte complexes were collected, counted and averaged to determine ovulation rate. Immunohistochemistry was used to determine the location of specific cell types in the ovary. We identified a specific population of monocytes, deemed ly6c^high monocytes, which infiltrate the ovary at a specific time. Immediately before ovulation occurs, ly6c^high monocytes are found in increased numbers in the ovaries, possibly to promote inflammation and follicular rupture. After ovulation, the numbers of these monocytes decreases rapidly, likely because once they enter the tissues they differentiate into either M1 macrophages, to further promote inflammation, or M2 macrophages to stimulate corpus luteum development. Studies have shown that animals deficient of these subsets of monocytes and macrophages have reduced rates of ovulation. Several other leukocyte populations were identified infiltrating the ovary, suggesting multiple leukocyte subsets are involved in ovulation. In this regard, in the ovary, the ly6c^highmonocytes may function as a source of M1 and M2 macrophages that initiate the inflammatory process and facilitate the rest of the reproductive process.

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