Presentations

Abstract

Introduction:

Space exploration has been a great interest for the United States since Neil Armstrong landed on the moon over fifty years ago. The Artemis mission to Mars will include equal numbers of female and male astronauts; therefore, it will be essential to determine how radiation affects women, specifically their ovarian health. There are four unique stages of follicle development. Primordial follicles are characterized by an oocyte surrounded by a singular layer of flat pre-granulosa cells. Primary follicles are characterized by an enlarged oocyte surrounded by a single layer of cuboidal granulosa cells. Secondary follicles are characterized by an oocyte surrounded by multiple layers of cuboidal granulosa cells without antral fluid. Finally, the last stage of follicle growth is the antral follicle, containing multiple layers of granulosa cells with antral fluid. Only antral follicles are able to erupt and release the oocyte for ovulation. During the voyage to Mars, the astronauts will be subjected to different levels and types of radiation. Destruction of these follicles will lead to decreased fertility outcomes. If galaxy cosmic radiation (GCR) is detrimental to an ovary's ability to grow and/or retain follicles, then GCR exposure should reduce the numbers of ovarian follicles.

Methods:

7-month-old adult female rats were divided into four groups: A FE10 (600 mEV) single exposure group, a double GCR (10 cGY each) exposure group, a GCR/He (10 cGY each) group, and a group that was not exposed to radiation (control group). All four groups of rats, which originated from Scottsdale, PA, were sent to the NASA Space Radiation Laboratory in Upton, New York, where they were irradiated, besides the control, and then shipped back to the Eastern Virginia Medical School laboratory. The ovaries were fixed in 10% formalin, processed using paraffin wax, and then sectioned using a microtome. Every fifth slide was stained using hematoxylin and eosin, and primordial, primary, secondary, and antral follicles were counted. Special care was given to counting the ovaries; only primordial and primary follicles with clear oocyte nuclei were counted, while for secondary and antral follicles, a clear oocyte nucleus and nucleoli had to be present to be counted. This was to prevent follicles from being overcounted. Total number of sections containing ovarian tissue was noted as a measure of overall ovary size.

Results:

To date, two ovaries have been fully analyzed: an ovary that was subjected to a double GCR exposure and a control ovary. Regarding follicle counts, the GCR-exposed ovary contained 141 primordial follicles, 45 primary follicles, six secondary follicles, and zero antral follicles. The control group ovary, on the other hand, contained 195 primordial follicles, 34 primary follicles, 17 secondary follicles, and zero antral follicles. Regarding ovary size, the GCR exposed ovary contained 269 total sections, while the control group ovary contained 595 total sections.

Conclusion:

Our preliminary results suggest that galaxy cosmic radiation may have a negative effect on the number of primordial and secondary follicles within an ovary and the overall size of the ovaries. This ongoing study will ultimately include multiple animals per group and two more radiation groups to compare the effects of different types of radiation on ovarian follicles. One particular area of concern for the female astronauts onboard the Artemis mission is the development of primary ovarian insufficiency. Sometimes called hypergonadotropic hypogonadism, it refers to the early loss of primordial follicles, which can lead to early loss of fertility and an earlier start to menopause in women. The observed reduction in primordial follicles observed in this preliminary experiment correlates with this phenomenon. Ultimately, this research may indicate the need for methods to reduce ovarian follicle loss, including improved guidelines for protective equipment for women astronauts.