Changes in progesterone concentrations in the Japanese long-fingered bat, Miniopterus schreibersii fuliginosus

Summary. In the Japanese long-fingered bat, when compared with the baseline values during non-pregnancy in the autumn, plasma progesterone concentrations were not significantly elevated during the delayed implantation stage that begins before the bats enter hibernation. However, progesterone concentrations were significantly lower dur-ing the delayed development stage that occurs during hibernation and rose significantly during the rapid embryogenesis that occurs after arousal from hibernation in the spring. Changes in the corpus luteum volume corresponded closely with those of plasma progesterone values. Maintenance of gravid females at 25\s=deg\Cfor 2 weeks in winter resulted in significant increases in the plasma progesterone concentration and the corpus luteum volume