Age-dependent telomere length changes in differentiating spermatogenic cells in azoospermic patients

Background. Telomeres are the terminal regions of chromosomes that play a crucial role in cellular aging and maintaining genomic stability. While telomere length decreases with age in somatic cells, an opposite trend is observed in spermatozoa. However, information on how telomere length changes during human spermatogenesis and its relationship with age remains incomplete.

Objective: To analyze the changes in telomere length during the differentiation of spermatogenic cells and to evaluate its association with the age in azoospermic patients.

Methods. The study was performed on testicular biopsy samples from 34 azoospermic patients aged 24-60 years. Cytogenetic preparations of colchicine-treated mitotic and meiotic metaphase plates were obtained from the samples. Telomere length was measured using quantitative fluorescence in situ hybridization (Q-FISH) on chromosomes from spermatogonia (n=483), spermatocytes I (n=305), and spermatocytes II (n=396).

Results. The telomere length in spermatogonia was shorter than in spermatocytes I (p=0.0234), and the telomere length in spermatocytes I was shorter than in spermatocytes II (p=0.0107). A positive correlation was observed between telomere length in spermatocytes II and the patients’ age (ρ=0.3966; p=0.0496). No association was found between the patients’ age and telomere length either in spermatogonia or in spermatocytes I (ρ=0.0643; p=0.7177 and ρ=-0.03297; p=0.8531, respectively).

Conclusion. Thus, in azoospermia, telomere length in spermatogenic cells increases from spermatogonia to spermatocytes I, and then to spermatocytes II; in spermatocytes II, it also increases with the patients’ ageing.

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