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Selected Spermatozoa at Conventional Magnification Cannot Guarantee in Obtaining Spermatozoa With Long Telomere Length in Severe Teratozoospermia Patients

Overview
Journal Cureus
Date 2025 Feb 10
PMID 39925560
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Abstract

Background Sperm selection from the population of processed spermatozoa cells after density gradient centrifugation (DGC) can assist embryologists in selecting high-quality sperm. Sperm selection of low-quality and chromatin-damaged spermatozoa is inevitable in severe teratozoospermia semen specimens. This study was conducted to evaluate whether sperm selection at ×400 magnification enables embryologists to select a population of spermatozoa with low DNA fragmentation and high sperm telomere length (STL) in semen samples with severe teratozoospermia. Methods A total of 23 infertile men characterized by severe teratozoospermia were selected. Sperm DNA fragmentation (SDF) and relative STL (r-STL) were evaluated at three stages: specimen collection, after DGC, and during the single selection of spermatozoa at ×400 magnification (single selection). The 23 patients were divided into two groups, including 14 with normal morphology ≤1% and nine with normal morphology of 2%. SDF and r-STL were compared between the two groups at three stages. Results The results of this study showed that although SDF decreased remarkably after DGC and single selection (F=64.327, P-value=0.000), the DNA fragmentation index obtained for each semen sample was more than the cutoff point of 18% based on the Halo sperm test. No statistically significant differences were observed in r-STL after DGC and single selection (F=1.978, P-value=0.163). Meanwhile, the pairwise comparison of r-STL showed that in the 2% normal morphology group, the mean relative telomere length was significantly higher in the selected spermatozoa compared to the semen specimen (P=0.014). This increase can be attributed to DGC and single selection by the embryologist. Also, there was no correlation between SDF and r-STL in the semen samples with severe teratozoospermia (r=0.01, P-value=0.964). Conclusions This study suggests that investing more time in sperm selection can decrease SDF, but r-STL of spermatozoa selected by the embryologist does not increase in severe teratozoospermia semen samples with morphology ≤1%.

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