Implications of ram sperm rheotaxis analysed by microfluidics for fertility.

Rheotaxis of sperm using a microfluidic device was explored in human, mice and bull. However, the rheotaxis of ram sperm and its role in fertility are unknown. Herein, we described the sperm rheotaxis in ram using microfluidic devices and focused on rheotaxis as potential markers of in vivo fertility. Computer-assisted sperm analysis (CASA) with controlled flow velocity was used to explore the kinematic parameters of sperm, total motility and positive rheotaxis (PR). The percentage of PR was defined as the number of PR sperm cells over the number of motile sperm cells. Then, according to the percentage of PR sperm, rams were classified into two groups; sperm with ≥40% PR and <40% PR, although the two ram groups showed similar total motility and kinematic values of sperm evaluated by CASA (p > .05). Two groups of rams mated one hundred thirty ewes naturally (10 ewes/ram). In the results, the pregnancy rate was higher in ≥40% PR (94.4%) than in <40% PR (42.5%, p < .05) after natural mating. Besides, the pregnancy loss was higher in <40% PR (33.3%) than in >40% PR group (8.1%, p < .05). In conclusion, the PR examination in semen can contribute to evaluate the reproductive performance of ram that will provide valuable insights into the semen evaluation.

Kisspeptin injection improved the semen characteristics and sperm rheotaxis in Ossimi ram.

The aim of the present study was to investigate the effect of kisspeptin-10 (Kp10) injection on semen characteristics, testosterone (T) production and sperm rheotaxis using microfluidic devices in immature ram. Computer-assisted sperm analysis (CASA) with controlled flow velocity was used to explore the kinetic parameters of sperm and positive rheotaxis (PR %). PR % was defined as the number of PR sperms over the number of motile sperms. Healthy Ossimi rams were randomly divided into two groups; a saline-treated control group and Kp10-treated one (5 µg/kg body weight). Treatments were given by intramuscular injection once a week for 1 month. After 1 month, the semen was collected and evaluated weekly for 6 weeks, while the blood samples were collected every 2 weeks for the next 8 weeks. Semen properties were significantly affected by Kp10 injection (p < .01). The Kp10 increased the volume, sperm concentration and percentages of live sperm compared with those of control. Additionally, sperm trajectories and rheotaxis get improved by the injection of Kp10 with time. Furthermore, kisspeptin improved the secretion of testosterone levels throughout the period of study. In conclusion, injections of the Kp10 had a positive impact on semen characteristics as well as improved sperm rheotaxis of Ossimi rams in subtropics.

Rheotaxis of sperm in fertile and infertile men.

Sperm rheotaxis refers to the ability of sperm cells to align their swimming direction with or against fluid flow. Positive rheotaxis (PR) is the tendency of sperm cells to swim against the flow. Herein, we describe sperm rheotaxis in fertile and infertile males, using a microfluidic platform and focus on rheotaxis as a potential marker of male fertility. A previously reported computer-assisted sperm analysis (CASA) plugin for Image-J was used to detect and analyze the motion of human sperm cells in microfluidic environments. The fabricated microchannels mimic the female reproductive tracts and use an image-processing program to monitor sperm swimming behavior in semen samples from fertile and infertile men. We have constructed an image-processing pipeline. The image-processing pipeline incorporated strengthens object detection and particle tracking to adapt to sperm that are out of focus while swimming on the same track. PR% was defined as the number of PR sperm cells over the number of motile sperm cells. The results showed that the percentage of PR correlates with fertility, wherein the fertile male specimens showed a higher PR% than the other groups (P < 0.05). There is no difference in progressive motility between the control group (fertile men with normal sperm analysis) and group 1 (G1; infertile men with normal sperm analysis). However, PR% was lower (P < 0.05) in the G1 group (13.5 ± 0.4%) compared to the control group (40.3 ± 3.3%) and group 2 (G2; infertile with reduced sperm motility) (15.3 ± 4.6%). Thus, PR% may be used as a novel parameter to explain infertility even in situations where basic sperm analysis following the World Health Organization (WHO) guidelines is unable to do so. We propose to use PR% as a novel parameter for sperm analysis and as a method of sperm selection in assisted reproductive technology.