Degree Type

Honors Capstone Project

Date of Submission

Spring 4-1-2008

Capstone Advisor

Dr. Melissa Pepling

Honors Reader

Dr. Eleanor Maine

Capstone Major


Capstone College

Arts and Science

Audio/Visual Component


Capstone Prize Winner


Won Capstone Funding


Honors Categories

Sciences and Engineering

Subject Categories



The development of primordial germ cells into oocytes is important for mammalian reproduction. Female germ cells first undergo a number of cell divisions resulting in the formation of cysts. Germ cell cysts are clusters of cells connected by intercellular bridges, formed by incomplete cytokinesis. The cysts breakdown after birth, resulting in individual oocytes that become surrounded by somatic pre-granulosa cells to form primordial follicles. During cyst breakdown two thirds of the original population of oocytes die. However, the processes by which cells within the cyst are designated to survive or die is not yet known. In addition, it is not yet known how primordial follicle formation is controlled. Evidence from other studies suggests that estrogen signaling might play a role in the process of early oocyte differentiation. The estrogen hormone regulates growth and differentiation in certain tissues through receptor-mediated pathways. Estrogen can signal through two different nuclear receptors called Estrogen Receptor alpha (ERa) and Estrogen Receptor beta (ERb). Previous studies have shown that ERa and ERb receptor specific agonists cause delays in cyst breakdown. The purpose of my thesis is to try to understand the role of signaling through ERa in the neonatal mouse ovary. ERa knockout mice, lacking ERa, were examined for defects in cyst breakdown, germ cell death, and follicle development. Ovaries were harvested from neonates during cyst breakdown of CD-1 wild type (+/+), heterozygous ERa (+/-), and homozygous ERa (-/-) knockout (ERaKO) mice. ERa knockout mice exhibited a slight difference in cyst breakdown at PND1 and PND7 and had lower oocyte numbers than did CD-1 wildtype mice. Effects on follicle development were overall inconclusive and further analysis is necessary. This research adds to knowledge of the role of ERa in cyst breakdown and sheds light on the mechanisms of oocyte differentiation.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

Included in

Biology Commons



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