Sperm morphology and its disorders in the context of infertility

This manuscript reviews sperm morphology and its disorders in the context of infertility. A new look into an old challenge is delivered, based on contemporary scientific and clinical evidence. We highlight the functional repercussions of sperm morphology aberrations and dissect the cause and effect of a variety of insults and pathogenic mechanisms focusing on the relationships among sperm shape, function, and compartmental analysis of cellular and subcellular structures. Different types of teratozoospermia are identified as a sequela of aberrant spermiogenesis, and their proven or speculated origins are discussed. In addition to known and suspected genetic causes, oxidative damage is highlighted as a major plausible pathogenic factor. The examination of sperm morphology with the use of strict criteria provides valuable information to guide the clinician to direct therapeutic management. We emphasize that sperm morphology is probably the most relevant parameter of the traditional semen evaluation and can be used as a valid biomarker of functional deficiencies, providing information about chances of conception. The information provided by the examination of sperm morphology as part of a complete semen analysis becomes more and more significant from a clinical point of view for infertility and perhaps men's health. (Fertil Steril Rev (R) 2021;2:75-92. (c) 2020 by American Society for Reproductive Medicine.)