Effect of in vitro storage of bovine spermatozoa on acrosomal integrity, proteolytic activity, binding, and initiation of penetration of oocytes.

During a 10-day 5 degrees C storage and subsequent 4-6-hr 37 degrees C incubation, both percent live spermatozoa and percent spermatozoa with an intact acrosome decreased, and percent spermatozoa with a late-reacted or without an acrosome increased. When stored spermatozoa were mixed with oocytes, no decrease in percent of oocytes with spermatozoa bound or percent of oocytes with spermatozoa starting to penetrate occurred as storage time increased. A 58% decrease in acrosin gelatinolytic activity and a 56% decrease in acrosin esterolytic activity but no decrease in nonacrosin proteolytic activity were evident over the 10-day storage. These studies show that a change in acrosomal morphology as well as a loss of acrosin may be responsible for the decreased fertility following extended in vitro storage of mammalian spermatozoa.