Cryopreservation enhances vacuolization in human spermatozoa

Abstract

Objective: To evaluate the impact of freezing–thawing on the human sperm head vacuoles and the potential value of motile sperm organelle morphology examination for selection of frozen-thaw spermatozoa.Methods: In 30 sperm samples from infertile men, analysis for conventional sperm parameters (motility, vitality, and normal morphology) and a morphological analysis at high magnification for vacuoles examination were done before cooling and after warming. For description of sperm head vacuoles, two hundred spermatozoa were examined and were classified into three groups according to presence and vacuole areas including no vacuole group (free of any vacuole), small vacuole group (occupy not more than 4% of the nuclear area), and large vacuole group (occupy more than 4% of the normal nuclear area).Results: Significant reduction of progressive motility and vitality was observed following cryopreservation (P<0.001). Also, normal morphology decreased significantly after cryopreservation (P<0.05). Spermatozoa with a vacuole-free head had a significant reduction in cryopreservation group (P=0.013). The percentage of spermatozoa with small vacuoles increased slightly, but not significantly after cryopreservation (P=0.296).Conclusions: Motile sperm organelle morphology examination is a powerful research tool for investigating spermatozoa abnormalities such as vacuoles that are increased post cryopreservation.

Keywords

• Freezing
• MSOME
• Spermatozoa
• Thawing
• Vacuoles