Estructura testicular y calidad seminal en ratones seleccionados por peso

Abstract

Reproductive female capacity was affected by the genetic selection performed in a pair of lines of two-way selection of body weight for 50 generations (s: downward selection; s': upward selection). These lines were originated from a control CF1 mice population (t) at the Faculty of Veterinary Sciences (UNR). The existence of reproductive differences attributed to the male genotype in the litter size and in the interval from the service beginning to first parturition was proven. With the aim of explaining them, the testicular structure - testicular weight (PTEST), vas deferens diameter (DTS), epithelium height (AES) - and the semen quality - spermatozoa number (NE), abnormal cell percentage (AN), motility and movement of spermatic cells (CASA parameters) were compared, in adult males between 10 and 14 weeks of age. The means of the DTS and AES were estimated for 100 seminiferous tubules per individual. Semen was obtained from the caudal portion of the epididymides and vasa deferentia. Sperm count was performed in Neubauer hemocytometer and abnormal cell percentage was estimated over 100 spermatozoa per sample. Motility parameters were determined with a Ceros 12.1 semen computerized analyzer. Body weight selection occasioned significant differences between lines in the same way of the selection performed for PTEST, AES and NE. Males of the heaviest line (s') show heavier testicles, higher seminiferous epithelium and, consequently, a higher number of spermatozoa when compared with s and t males (p<0,05). Semen quality under the employed setup conditions was similar for males of the three lines. Therefore, semen quality does not contribute to the explanation of the fertility differences between lines.