Received August 18, 2021
Accepted February 21, 2022

Objective: The purpose was to investigate the cellular and molecular levels of apoptosis induction in three groups of the male partner of infertile couples with normal sperm parameters and unexplained male infertility, those with abnormal sperm parameters, and fertile men as controls. Methods: Twenty-five infertile men with abnormal sperm and 25 men with UMI and normal sperm parameters were recruited as experimental group I and experimental group II. 25 fertile men were included as the controls. The mRNA levels of Fas, Fas ligand, Caspase 8, Bax, and Bcl2 were measured in three groups. The cellular rates of early and late apoptosis were assessed using annexin V and propidium iodide staining. Results: The expression of Bax, Bcl2, and Bax / Bcl2 ratio in experimental group I was significantly higher than that in experimental II and control groups. However, the ratio of Bax / Bcl2 was less than 1 among all groups. No significant difference was found among study groups regarding the gene expression of Fas, Fas ligand, and Caspase 8. No significant difference was seen in early apoptotic rates of sperm among all study groups. The highest number of necrotic sperm cells was detected in experimental group I. Conclusions: The findings showed that the external pathways of apoptosis were not activated in the absence of external stimuli of sperm apoptosis in ejaculated sperm. Independent of fertility status, apoptosis gene induction in the internal pathway was associated with abnormalities in sperm motility and/or morphology in men with abnormal parameters.