Rat dorsal prostate is necessary for vaginal adhesion of the seminal plug and sperm motility in the uterine horns

The rat prostate comprises dorsal, ventral and lateral lobes that are morphologically and biochemically distinct. Lesions to these structures are expected to affect the quality of the ejaculate and male fertility. In experiment 1, we analyzed ejaculate parameters of males that had chemical lesions of the dorsal or ventral lobes. At pre-lesion and at 5 and 20 days post-lesion males were mated, and after ejaculation, seminal fluid and seminal plug were obtained from the mated females. In experiment 2, the ventral lobes were ablated, and the ejaculate was analyzed. In experiment 3, the fertility of males with chemically-lesioned dorsal lobes or ablation of the ventral lobes was evaluated. Chemical lesion of the dorsal lobe prevented the adhesion of the seminal plug to vaginal walls. When these males were tested at 5-days postlesion, no sperm were found in uterus, and at 20-days post-lesion, the few sperm encountered showed slow progressive motility. None of the females that mated with dorsal lobe-lesioned males became pregnant. However, chemical lesion or ablation of the ventral lobes did not affect ejaculate or fertility. Our results indicate that the dorsal prostatic lobes are indispensable for reproductive success in males, and define parameters of ejaculate with which fertility can be estimated.

Análisis de los parámetros del eyaculado en la rata Wistar de laboratorio: descripción de la técnica / 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 mm3 . 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.

Se ha cuantificado en el eyaculado de la rata de laboratorio, el número de espermatozoides, peso y tamaño del tapón seminal, y en muestras obtenidas de epidídimo, la viabilidad, movilidad y concentración espermáticas. Los valores de referencia para el eyaculado de la rata no se han determinado quizá por la dificultad para obtenerlo directamente del macho. No obstante, puede obtenerse una aproximación al analizar el eyaculado recolectado de una hembra recién inseminada. El objetivo de este estudio fue evaluar y proponer los valores de los parámetros macroscópicos y microscópicos del semen y tapón seminal obtenidos de la hembra. El análisis del semen de ratas Wistar se realizó adecuando los métodos usados para otras especies. Después de una serie eyaculatoria, se obtuvo el semen contenido en los cuernos uterinos y el tapón seminal de la vagina. En más de 100 eyaculados, 94.54% fueron blanquecinos, con 2.35 ± 0.06 mm de viscosidad y 8.13 ± 0.02 de pH. La concentración espermática fue de 16.3 ± 0.59 millones de espermatozoides por mL, 0.72 ± 0.01 de índice de movilidad, 64.4 ± 0.7% de viabilidad y 99.11 ± 0.20% de morfología normal. Del 99% de los tapones seminales, 92.7% fueron endurecidos, pesaron 115.63 ± 1.54 mg, midieron 12.41 ± 0.13 y 5.31 ± 0.05 mm de largo y ancho, respectivamente, y de volumen 87.70 ± 1.74 mm³. En conclusión, el método utilizado para obtener y evaluar los parámetros del eyaculado es confiable, por ello se sugiere que los resultados obtenidos podrían considerarse como valores indicativos para el semen y tapón seminal de la rata Wistar.