Sperm production and seminal analyses in a Neotropical sperm-storing vespertilionid bat yellowish myotis (Myotis levis)

• Published in: Theriogenology 2021-10, Vol.174, p.73-84
• Main Authors: Farias, Talita De Oliveira, Figueiredo, André Felipe Almeida, Wnuk, Natalia Teixeira, Vieira, Carolina Pinhol, Lara, Nathalia de Lima e Martins, Avelar, Gleide Fernandes de, Talamoni, Sônia Aparecida, Costa, Guilherme Mattos Jardim
• Format: Article
• Language: English
• Subjects: Chiroptera; Seasonal reproduction; Seminal parameters; Sperm production; Spermatogenesis duration
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2021.08.018

Yellowish myotis is a Neotropical vespertilionid bat that presents a seasonal reproduction. The sperm is produced in the Mature stage, stored in the Regressed stage and released in the Rest stage (mating period). Aiming to understand, for the first time, the relationship between testis and epididymis physiology in yellowish myotis reproduction, the spermatogenesis length, sperm production, and seminal parameters were herein evaluated. Fifty-one adult male bats were captured in Santuário do Caraça, Minas Gerais, Brazil. The gonads were collected in the Maturing and Mature stages for histomorphometric and immunohistochemical analyses, whereas the epididymis was evaluated in all reproductive stages for seminal studies. Our results demonstrated that the yellowish myotis spermatogenic process is fast, lasting 31.70 ± 0.15 days. Despite the low Sertoli cell efficiency (6.60 ± 1.23), the high numbers of Sertoli cells per testis enable an elevated sperm production in the Mature stage. The sperm concentration, vitality, and motility presented the highest values in the Regressed stage; however, in this period, an increased incidence of sperm morphological defects was detected. In the following period (Rest stage), a drastic reduction of defective sperm was observed, suggesting quality control of sperm before the mating period. Furthermore, the epididymis ability to maintain a long-term sperm-storage was observed in 26.7% of the bats in the Maturing stage. In summary, yellowish myotis presented a fast and high sperm production during the Mature stage. These sperms are stored and selected before mating period. •Yellowish myotis presents a fast spermatogenesis length.•Yellowish myotis has a high sperm production at a restricted time.•Seminal parameters of yellowish myotis were described in all reproductive stages.•The epididymis of yellowish myotis maintains long-term sperm storage.•Defective sperm is eliminated prior to the mating period.