Relationship between spermatogenesis, DNA fragmentation index, and teratozoospermia index

Infertility has proven a global medical issue, with 15-20 percent of married worldwide experiencing difficulties in conceiving. One of the causes of male infertility is sperm morphology abnormalities, or teratozoospermia, which is often associated with sperm DNA damage. Teratozoospermia can increase sperm DNA fragmentation through several mechanisms, including abortive apoptosis and induce ROS formation. Unfortunately, many forms of sperm flaws, including genetic defects, could not be validated by routine semen examination. In the Sixth Edition, WHO introduced a more thorough sperm morphology examination, named the teratozoospermia index (TZI), in which every aberrant sperm is examined for up to four defects. Analyzing spermatozoa abnormalities in more detail can provide an overview of the function of the male reproductive organs, particularly the testes and epididymis. However, using this method is not entirely easy due to subnormal variations between cells so that quality control may be needed when using TZI for sperm morphology evaluation