Effect of pH value of freeze-drying solution on the chromosome integrity and developmental ability of mouse spermatozoa

Abstract

The nuclie of freeze-dried mouse spermatozoa are able retain their chromosome integrity and developmental potential. To optimize the conditions of freeze-dying, we examine whether pH values of the freeze-dying solution affect the chromosome integrity and developmental potential of sperm nuclie. The sperm freeze-dying solution we used contained a high concentration (50 mM) of calcium-chelating EGTA. Sperm chromosomes were examined at he metaphase of the first mitosis after injection of the freeze-dried spermatozoa into matures oocytes. The developmental potential of sperm nuclei was assessed by examining the developmental of fetuses in midgestion. The results showed that both sperm chromosomes and sperm developmental potential are maintained better when the freeze-drying solution was slightly alkaline (pH 8.0) rather than near neutral or acidic (pH 7.4-6.0). The data indicated that the chromosome integrity and developmental ability of mouse spermatozoa are affected by the pH value of freeze-dying solution.