Male Reproductive Patterns of Hibernating Korean Greater Horseshoe Bat, Rhinolophus ferrumequinum korai: I. Annual Cycle of the Seminiferous Epithelium and Morphological Changes of the Testes

Background: Morphological changes of testes and seminiferous epithelium cycle were observed by optical and transmission electron microscopy to determine male reproductive patterns of the hibernating Korean greater horseshoe bat, Rhinolophus ferrumequinum korai. Materials and methods: In this study, 40 male Rhinolophus ferrumequinum korai were collected from abandoned mines in Gyeongnam and Jeonnam provinces of South Korea from January 2014-December 2015. Differentiation process and cytological traits of seminiferous epithelium following monthly changes were examined with electron microscopic techniques and observed by optical and electron microscopy. Results and conclusion: Male reproductive pattern of hibernating Korean R. ferrumequinum korai consists of three main stages. The first is the spermatogenesis stage (from April-September), including spermatocytogenesis (which appears from April-May) and spermiogenesis (from June-September). The activity of spermatogenesis was the highest in August. The lumen of seminiferous tubules was open from mid-April to mid-October. It was closed from November to March of the following year. The second is the phagocytosis stage (from mid-Octobermid-November) that is a purification process to prepare for new spermatogenesis the following year. This period is called the cleansing period. The third is the dormant stage that is a state of holding only spermatogonia and Sertoli cells. It is an adaptation strategy to store energy for long periods of hibernation. Compared to previous studies [1], spermatogenesis period preceded one month earlier. This suggests that temperature increase can impact reproductive development and spermatogenesis.