PLATELET-ACTIVATING-FACTOR ENHANCES THE ACROSOME REACTION, FERTILIZATION IN-VITRO BY SUBZONAL SPERM INJECTION AND RESULTING EMBRYONIC-DEVELOPMENT IN THE RABBIT

This study was conducted to investigate the effect of platelet activat ing factor (PAF) on the acrosome reaction and fertilizing capacity of spermatozoa, and development of the resulting embryos in the rabbit. R abbit spermatozoa were exposed to PAF, lyso-PAF, or high ionic strengt h medium (HIS) prior to subzonal sperm injection (SUZI) into 326 matur e oocytes, or morphological assessment of the acrosome reaction. The r ates of fertilization and blastocyst formation were compared among the three treatment groups. Acrosome reaction was assessed by fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) stainin g and electron microscopy. PAF-treated spermatozoa fertilized the oocy tes at a significantly higher rate (56.1%) than did lyso-PAF- (36.8%, P < 0.01) or HIS- (38.2%, P < 0.05) treated spermatozoa. The embryos p roduced by PAF-treated spermatozoa showed significantly higher blastoc yst formation rates (34.0%) than lyso-PAF- (8.6%, P < 0.05) or HIS- (8 .8%, P < 0.05) treated spermatozoa. FITC-PSA staining demonstrated a s ignificantly higher incidence of acrosome reaction in PAF-treated sper matozoa (45.8%) than in lyso-PAF- (28.0%, P < 0.01) or HIS- (34.9%, P < 0.01) treated spermatozoa. Acrosome reaction of PAF-treated spermato zoa was also confirmed by electron microscopy. PAF treatment of sperma tozoa enhances fertilizing capacity for SUZI possibly by augmenting th e acrosome reaction. Enhanced embryonic development was also found in the oocytes fertilized by SUZI of PAF-treated spermatozoa.