Annual male reproductive activity and stages of the seminiferous epithelium cycle of the large fruit-eating Artibeus lituratus (Chiroptera: Phyllostomidae)

The large fruit-eating phyllostomid bat, Artibeus lituratus (Olfers, 1818), forearm 69-75 mm, body mass 66-82 g, has a diversified geographic distribution in the Neotropical region. Therefore it is subjected to different climatic conditions that affect its reproduction, leading to different reproductive strategies such as continuous reproduction, seasonal monoestry or seasonal bimodal polyestry. In this study we used morphometric and histological methods to analyze the annual reproductive activity of A. lituratus males in a population living in the Atlantic Forest, Southeastern Brazil. Testis mass, epididymis mass, gonadosomatic index, seminiferous tubule diameter, and Leydig cell nucleus diameter showed no significant differences (p > 0.05) in the two seasons (wet: October to March; dry: April to September). Additionally, the cauda epididymis was packed with sperm throughout the period of study. Our data indicate that in this population spermatogenic activity was continuous throughout the year. Slight variations in accumulated frequency of pre-meiotic, meiotic and post-meiotic stages of the seminiferous epithelium cycle were observed when compared to other bat species, probably due to species-specific characteristics.

大食果叶口蝠（Artibeus lituratus, Olfers, 1818）前臂长69~75 mm，体重66~82 g，在新热带区拥有多样化的地理分布。因此该物种会面临影响其繁殖的多样气候条件，进而演化出多种繁殖策略，包括持续繁殖、季节性单发情繁殖以及季节性双峰多发情繁殖。本研究采用形态测量学与组织学方法，对栖息于巴西东南部大西洋森林的该物种雄性种群的年度繁殖活动开展分析。结果显示，睾丸质量、附睾质量、性腺指数（gonadosomatic index）、生精小管直径以及莱迪希细胞（Leydig cell）细胞核直径在两个季节（湿季：10月至次年3月；干季：4月至9月）均无显著差异（p > 0.05）。此外，在整个研究周期内，附睾尾部（cauda epididymis）始终充满精子。本研究数据表明，该种群的生精活动全年持续。与其他蝙蝠物种相比，生精上皮周期的减数分裂前、减数分裂及减数分裂后阶段的累积频率仅存在细微差异，这大概率源于该物种的特异性特征。