Annual Cycle of the Seminiferous Epithelium of Myotis macrodactylus

Abstract

The annual cycle of Myotis macrodactylus seminiferous epithelium and morphological features of spermatids during spermiogenesis were observed using a light microscope. Seminiferous tubule diameters gradually began to increase from April (60-63;d;m) in the early arousal period, attained a peak in July (172-175~lm), and decreased rapidly to the size in October (70-75jum), and gradually decreased to March (48-50lhm) the next year. M. macroducylus spermatogenesis begins in April, peaks in mid summer (July) and is suspended from October to March in the next year. Spermatocyiogenesis have occurred from April to June only. Sperrniogenesis occurred from July to September. The transformation of spermatids into spermatozoa M. macrodactylus was divided into six stages. When the mating periods were finished, from October, the redundant spermatogenic cells in the seminiferous tubules were engulfed by phagocytosis of Sertoli cells, and ~hagocytosis was continually observed from November to March the next year. During the phagocytosis, the seminiferous tubule contains only Sertoli cells and sperrnatogonia. The lumen of the serniniferous tubules was opened from July to September, and closed from October to June the next year. Therefore, the male reproductive of the Korean bat, M. macroductylus belong to Pcp~strellus pattern according to the opinion of Gustafson (1979). These results suggest that the adaptive strategy for long hibernation serves as the mechanism to regulate the breeding cycle.