Analysis of the parameters of the ejaculate in the laboratory Wistar rat: technical description

The number of spermatozoa, weight and size of the seminal plug has been quantified in the ejaculate of the laboratory rat and sperm viability, sperm mobility and sperm concentration in samples obtained from the epididymis. The reference values for the rat ejaculate have not been determined maybe due to the difficulty to obtain it directly from the male. Nevertheless, an approach can be obtained analyzing the ejaculate collected from the inseminated female. The objective of this study was to evaluate and propose the values of the macroscospic and microscopic parameters of the semen and seminal plug obtained from the female. The seminal analysis of the Wistar rats was performed adapting the methods used for other species. After one ejaculatory series, semen contained in the uterine horns was obtained, as well as the seminal plug from the vagina. In more than one hundred ejaculates, 94.54% were off-white with 2.35 +/- 0.06 mm of viscosity and 8.13 +/- 0.02 of pH. The sperm concentration was 16.3 +/- 0.59 millions of spermatozoa per mL, 0.72 +/- 0.01 mobility index, 64.4 +/- 0.7% viability and 99.11 +/- 0.20% normal morphology. From 99% of seminal plugs, 92.7% were hardened, they weighed 115.63 +/- 1.54 mg, measured 12.41 +/- 0.13 and 5.31 +/- 0.05 mm of length and width respectively, and volume 87.70 +/- 1.74 mm(3). In conclusion, the used method to obtain and to evaluate the parameters of the ejaculate is reliable, for that reason, it is suggested that the results obtained could be considered as indicative values for semen and seminal plug for the Wistar rat.