Following sacrifice twelve hours postflight, the testes were removed, weighed, and immediately slit open and immersed in Triple Fix. Six blocks were produced from each testis. All of the samples were treated with 1% osmotic acid for one hour, dehydrated in acetone, infiltrated with Epon-Araldite, and polymerized at 60 degrees C. Two-micron cross sections of the tubules were cut on a microtome, mounted on slides, and stained. Alternate sections containing maturation stage six were used to count the surviving spermatogonia.

Results:

The average weight loss of the flight rat testes was 7.1% as compared to the controls. Counts of the stage six spermatogonial cells showed a significant decrease (7.5%) in cell population. The testis is known to be very sensitive to many environmental factors, including radiation and stress, and dosimetry from previous Shuttle flights indicated a dose factor of approximately 0.05 rad would occur in the animal area. Since it would take about one rad of cosmic rays to reduce the measured cell population by the observed amount, radiation cannot be considered the primary cause; stress from adapting to weightlessness and the final jet flight or other factors must also be considered. These findings need to be repeated with accurate dosimetry to determine if radiation had any effect. Also, additional measurements need to be made to determine the role stress has played in decreasing the weight and population of spermatogonial cells.