An investigation of sperm migration into the oviducts of the mare.

This study investigates the movement of sperm into mares’ oviducts post insemination using both freshly ejaculated and frozen sperm. The research indicates that regardless of the sperm origin (fresh or frozen), the time of semen migration, and the section of the oviduct examined, no significant differences were found in the amount of migrated sperm.

Research Process

• For this study, a total of 23 mares were inseminated once within 0-6 hours after ovulation was clinically detected.
• 14 mares were inseminated with fresh semen, and the other 9 were inseminated with deep-frozen semen, the sperm count in both ranging from 0.1 x 10(9) to 4.7 x 10(9) motile spermatozoa.
• After insemination, the mares were slaughtered at intervals of 2, 4, or 6 hours, and their genital tracts were then removed for examination.

Examination Process

• The genital tracts were segregated into different regions including the utero-tubal junction, isthmus, and ampulla, and the regions were rinsed separately for sperm recovery.
• In some mares, the uterine horn and corpus uteri, cervix, and vagina were also rinsed.
• Microscopic tissue samples were collected from the flushed areas and prepared for scanning electron microscopy to visualize sperm distribution in situ.

Research Findings

• This study found no significant differences in sperm migration and sperm count in the different regions of the mare’s oviduct 2, 4, or 6 hours after insemination, irrespective of whether the sperm was from fresh or frozen semen.
• However, the greatest number of sperm were found at 4 hours after insemination across all the examined sites.
• The scanning electron microscope did not reveal any alterations in the sperm-head membranes that could be linked with sperm capacitation.
• Most of the sperm found in the uterotubal junction, isthmus, and ampulla displayed morphological integrity, indicating that they weren’t damaged by the transit process.