Effect of Cryopreservation on Vital and Morphological Parameters of Spermatozoa: A Laboratory-Based Investigation

Abstract

Sperm cryopreservation is a crucial procedure in Assisted Reproductive Technology (ART); 
however, it is known to adversely affect the quality of recovered spermatozoa. This study aimed to 
evaluate the impact of the freezing and thawing processes on the vital and morphological parameters of 
spermatozoa. The study included 40 semen samples obtained from men with normal semen parameters 
attending the Al-Sgaaf Center for Infertility Investigations in Mukalla, Hadhramout, Yemen, between 
December 2022 and March 2023. Semen samples were analyzed pre-freezing and post-thawing 
according to the World Health Organization guidelines. The results of the study revealed a highly 
statistically significant decline (p < 0.001) in sperm quality following cryopreservation. The mean total 
motility decreased remarkably from 63.2% to 50.6%, and sperm vitality dropped from 63.9% to 52.4%. 
Furthermore, normal sperm morphology was severely affected, with the total percentage of 
morphologically normal spermatozoa decreasing from 35.8% before freezing to 25.9% after thawing. 
Regarding specific sperm regions, the normal morphology of the head declined from 23.0% to 12.1%, 
the midpiece from 45.6% to 41.0%, and the tail from 41.5% to 35.9%. In conclusion, the 
cryopreservation process causes a substantial deterioration in sperm motility, vitality, and normal 
morphology, highlighting the urgent need to develop optimized cryopreservation protocols and better 
cryoprotectants to minimize cellular stress and damage during the freeze-thaw cycle