Effect of Osmolality and Glycosaminoglycans on Motility, Capacitation, Acrosome Reaction, and In Vitro Fertilizability of Bovine Ejaculated Sperm

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Abstract
Bovine ejaculated semen was placed in a modified Tyrode''s medium with albumin, lactate, and pyruvate. The sperm were washed three times and subjected to nine treatments in a 3 .times. 3 factorial arrangement. Treatments consisted of osmolality (exposure to 380 mOsmol/kg medium for 5 min, exposure to 340 or 295 mOsmol/kg medium for the entire incubation period), and the presence or absence of glycosaminoglycans (100 .mu.g/ml chondroitin sulfate A or 10 .mu.g/ml heparin). Sperm were examined at 4.5 h, 8 to 9 h, and 24 to 25 h of incubation (37.degree. C, 5% CO2, and 95% air). Heparin caused head-to-head agglutination of sperm, raised the percent sperm without seminal antigens over the acrosome (capacitated) by 20% at 4.5 h, and doubled the percent of acrosome-reacted sperm. However, this stimulation did not improve in vitro fertilizability. Chondroitin sulfate A tended to maintain motility, but did not affect capacitation or the acrosome reaction, possibly due to glucose inhibition. Both high osmolality treatments tended to reduce motility, especially after 24 h of incubation when the 340 osmolality treatment reduced motility by 14% over the 295 treatment. No consistent effect on capacitation was observed. The 340 and 380 osmolality treatments induced 8.6 and 6.1% more acrosome reactions by 24 h than the 295 treatment. The 340 mOsmol/kg treatment yielded insignificantly higher in vitro fertilization rates, as evidenced by development of zygotes to the two-cell stage. Lack of statistical significance was due to high variation with in vitro fertilization rates.