Binding of stallion spermatozoa to the equine zona pellucida after coculture with oviductal epithelial cells.

This study aims to investigate whether the process of capacitation, a necessary phase stallion sperm cells undergo in order to fertilize an egg, is facilitated by co-culturing the sperm with mare oviductal epithelial cells. Through comparisons across different treatment methods and staining techniques, the researchers document significant differences between bound and unbound sperm cells and the degrees to which each display signs of capacitation.

Objective and Overview

• The main objective of this research was to determine if the incubation of stallion sperm cells with mare’s uterine tubal (oviductal) epithelial cells could trigger sperm cell capacitation (the process that sperm undergo to be able to fertilize an egg) in a lab setting.
• The research compares three scenarios: stallion sperm cells incubated with (1) a medium only (negative control), (2) a calcium ionophore A23187 (positive control, known to induce capacitation), and (3) mare’s oviductal epithelial cells for 4 hours.

Methodology

• The research used chlortetracycline staining to effectively identify the capacitated or acrosome-reacted sperm cells by their patterns.
• The attached sperm cells to the zona pellucida (the outer layer of the egg) were stained for evaluation right after initial binding (pulse) and after 1 hour of co-incubation (chase).

Key Findings

• Significantly more sperm cells in the ionophore and oviductal epithelial cell treatments were bound to the zona layer at both the pulse and chase stages than those in the control medium.
• More bound sperm cells were found capacitated at the pulse stage, and acrosome reacted at the chase stage, for both ionophore and co-culture groups than the control groups.
• The patterns of bound sperm cells to the zona pellucida varied distinctly when compared to sperm cells not bound to the zona pellucida within each treatment.
• Pulse stage results showed a higher percentage of capacitated sperm cells and a lower percentage of acrosome-reacted sperm cells bound to the zona compared to the proportions found in the treatment suspensions of sperm cells.