Effect of Simulated Microgravity on Sexual Development of Female Japanese Quail

Abstract

Hypodynamia is a method to simulate weightlessness (microgravity) in the laboratory conditions. The objective of this study was to investigate the influence of chronic hypodynamia on the growth and development of the ovary and oviduct, plasma estradiol and progesterone concentration, and the onset of egg-laying in Japanese quail. The ovary weight gradually increased with age in both groups. However, the experimental birds subjected to hypodynamia showed a significant reduction in ovary weight relative to age-matched control between 21 and 42 days of age (P < 0.05). The number of yellow follicles with a diameter of less than 10 mm, between 10 and 15 mm and more than 15 mm was similar in both groups from 49 days to the end of experiment. The control birds had significantly longer oviduct than those of the test group from 28 to 63 days (P < 0.05) with the exception of day 49. The quail reared under hypodynamia laid their first egg about three days later than control. Plasma progesterone concentration in experimental quail was significantly reduced between 28 and 49 days (P < 0.05). Plasma estradiol concentration increased progressively with age in both groups. The differences between the groups were not significant at any age. These findings suggest that although hypodynamia negatively affects some of the examined variables, the female Japanese quail is able to grow and develop normally under conditions of simulated weightlessness.