1. Sperm to zona pellucida binding depends on the use of a gonadotropin-releasing hormone agonist or a gonadotropin-releasing hormone antagonist 
Annika K Schröder, M.D., Beate Schöpper, Sc., Ph.D., Safaa Al-Hasani, V.D., Martin Löning, M.D., Klaus Diedrich, M.D., Michael Ludwig, M.D. 
Fertility and Sterility 
Volume 79, Issue 3, Pages (March 2003)
DOI: /S (02)

2. FIGURE 1
Sperm zona pellucida binding in oocytes derived from GnRH agonist (triptorelin) or GnRH antagonist (cetrorelix) cycles. Differences in the sperm–zona binding capacities were statistically significant, independent of the use of either rhFSH or HMG. Black bar = rhFSH, white bar = hMG, gray bar = total.
Schröder. Sperm-oocyte binding and GnRH antagonist. Fertil Steril 2003.
Fertility and Sterility  , DOI: ( /S (02) )