The epididymal microenvironment in Akodon cursor (Muridae, Sigmodontinae, Akodontini): The lifetime of spermatozoa from production to maturation

Abstract

Sperm fertility in mammals depends on the complexity of several physiological events. The male gamete is produced in the testis and matured in the epididymis, which requires an adequate environment for sperm maturation and survival. This study focused on characterizing the sperm morphology of the small wild rodent Akodon cursor and describing the epididymal environment supporting sperm maturation. Eight A. cursor males were captured from a preserved area of the Atlantic Forest in Viçosa (MG, Brazil). The epididymides were processed for histological, functional, and proteomic analyses, besides sperm quality evaluation. Data were submitted to ANOVA and the post hoc Tukey's test (P < 0.05). The length of A. cursor sperm was 52.71 ± 0.79 μm (mean ± SD), with 5.12 ± 0.07 μm corresponding to the nucleus. Sperm motility and vigor were 45.6 % ± 2.9 and 2.9 ± 0.2, respectively. The duration of sperm transit time in the epididymis was 2.75 ± 0.22 days. Histomorphometrically, the distal cauda had the highest tubular and luminal diameter, whereas the epithelial height was higher in the initial segment than in the other regions. Proteomic analysis identified 56 proteins in the proximal epididymal regions of A. cursor related to crucial processes, including cellular homeostasis, flagellar elongation, and the elimination of defective sperm during epididymal transit. These findings provide valuable insights into the molecular mechanisms underlying sperm maturation in this species. In conclusion, the epididymis of A. cursor shares similarities with other rodent species but exhibits unique characteristics, such as shorter sperm transit time.