Selection of human spermatozoa by a hyperosmotic two-layer Percoll gradient

Abstract

Objective: To investigate whether a hyperosmotic Percoll solution improves the spermatozoal recovery rate of a two-layer Percoll gradient.

Design: A total of 49 semen samples were prepared by both the conventional two-layer Percoll gradient and a hyperosmotic Percoll gradient.

Setting: In vitro fertilization laboratory of a tertiary care, university-affiliated hospital.

Patients: Semen samples were obtained from patients attending semen analysis.

Main outcome measures: The number of spermatozoa recovered, percentage motility, percentage normal morphology, and their survival at 24 hours were assessed after preparation by both Percoll gradients.

Results: The hyperosmotic Percoll gradient resulted in a significantly higher total and motile sperm recovery rate. The degree of increase in total sperm recovery was significantly higher in abnormal semen samples compared with normal semen samples. Percentage normal morphology of sperm samples prepared by hyperosmotic Percoll was improved compared with conventional Percoll but was only significant in abnormal semen samples. However, percentage motility of sperm samples prepared by the hyperosmotic Percoll was significantly lower than those prepared by conventional Percoll gradients.

Conclusions: The hyperosmotic two-layer Percoll gradient improved motile sperm recovery but also recovered more immotile sperm, leading to a decrease in percentage motility. This technique may allow us to recover more spermatozoa when we come across samples of low sperm concentration.