[Correlation between functional and ultrastructural status of spermatozoa (based on transmission electron microscopy...

Standard diagnostic testing for male infertility includes a spermogram in accordance with current World Health Organization (WHO) recommendations. However, a basic ejaculate examination is insufficient to identify the causes of unsuccessful conceiving attempts, early pregnancy terminations, and ineffective ART protocols. Modern methods include transmission electron microscopy (TEM) of sperm, which allows visualization of their ultrastructural elements, and the HBA (Hyaluronan Binding Assay) test, which assesses the functional maturity of sperm. The clinical significance of these methods lies in their ability to detect hidden disorders of spermatogenesis, assess sperm DNA quality, and determine the functional readiness of gametes for fertilization.

To establish a relationship between the level of functional maturity of spermatozoa, determined using the HBA test, and the presence of ultrastructural changes detected using electron microscopic examination of spermatozoa.

The retrospective study included 98 men who sought medical help due to marital infertility. The average age was 33.5+/-4.2 years; the duration of infertility was 2.4+/-1.9 years. All men underwent ultrasound examination of the scrotum, determination of testosterone, LH, FSH, prolactin, and estradiol levels in the blood serum, spermogram, HBA test, and EMIS. Sperm analysis for both tests was performed from one portion of ejaculate. The men were stratified into two groups: group 1 - patients with HBA test < 65% (n=21) and group 2 - with HBA test > 65% (n=77). The study groups did not differ in age, anthropometric data, hormonal profile indicators, incidence of varicocele, and bad habits.

Semen analysis revealed a significant reduction (p<0.01) in the main ejaculate parameters in the group with impaired functional sperm maturity compared with the control group: sperm concentration (38.8+/-10.3 million/ml vs. 64+/-5.8 million/ml, respectively), total sperm count per ejaculate (125+/-32,5 million vs 229+/-23,1 million), progressive motility (44,8+/-5,4% vs 60+/-2,5%), and normal morphology (1,9+/-0,7% vs 3,6+/-0,42%). According to TEM data, the presence of an acrosome on the sperm head (R=0,343, p=0,002) and an intact postacrosomal sheath (R=0,248, p=0,024) showed a weak positive correlation with the HBA test, whereas reduced acrosomal size (R=0,227, p=0,039) and reacted acrosomes (R=0,295, p=0,007) demonstrated a weak negative correlation with the HBA test. Chromatin decondensation (R=0,353, p=0,001) and the presence of a cytoplasmic droplet on the sperm head or neck (R=0,427, p=0,001) were negatively correlated with the HBA test. In patients with an HBA test value <65%, there was a positive correlation with the presence of an acrosome (R=0,759, p=0,0001), its normal position (R=0,557, p=0,009), and normal axonemal structure (R=0,449, p=0,041), and a negative correlation with reduced acrosomal size (R=0,541, p=0,011), reacted acrosomes (R=0,683, p=0,001), and abnormal chromatin structure (R=0,467, p=0,033) on TEM.

Reduced sperm binding capacity to hyaluronic acid is associated with ultrastructural sperm abnormalities. Assessment of functional sperm maturity using the HBA test serves as a predictor of ultrastructural defects in spermatozoa and is of considerable clinical relevance.