The first stage in the analysis of male fertility is the analysis of ejaculate (spermogram). Very often, with normal indicators of spermogram, fertilization does not occur. One of the causes of this phenomenon is the immature sperm, that is, the spermatozoon is not able to bind to the oocyte shell. Only mature sperm, during the natural fertilization process, interacts with hyaluronic acid with the aid of special receptors on the membrane. Hyaluronic acid (hyaluronate) is a heteropolysaccharide, which is part of the extracellular matrix of cumulus cells surrounding the egg cell. Only mature sperm have this property, and hence the ability to fertilize and form an embryo of high quality.
The evaluation of the maturity of spermatozoa can be done under laboratory conditions using the HBA test. This test is often prescribed together with a spermogram as an additional research method. Spermatozoa that are capable of binding to hyaluronic acid have normal morphology, normal levels of DNA fragmentation, without excessive cytoplasm residue or preservation of histone proteins – that is physiologically functional (mature). According to the results of the HBA test, the spermatozoa index is determined. Normally, it should reach 60-80%. If the index is less than 60%, then this indicates the probability of male infertility (even with normal spermograms) and requires the use of ART methods.