Diagnostic tools in male infertility-the question of sperm dysfunction

Abstract

Sperm dysfunction is the single most common cause of infertility, yet what is remarkable is that, there is no drug a man can take or add to his spermatozoa in vitro to improve fertility. One reason for the lack of progress in this area is that our understanding of the cellular and molecular workings of the mature spermatazoon is limited. However, over the last few years there has been considerable progress in our knowledge base and in addressing new methods to diagnose sperm dysfunction. We review the current state of the field and provide insights for further development. We conclude that: (i) there is little to be gained from more studies identifying/categorizing various populations of men using a basic semen assessment, where an effort is required in making sure the analysis is performed in an appropriate high quality way; (ii) technological development is likely to bring the reality of sperm function testing closer to implementation into the clinical pathways. In doing this, these assays must be robust, cheap (or more appropriately termed cost effective), easy to use and clinically useful; and (iii) clinical necessity, e.g., the need to identify the highest quality spermatozoon for injection is driving basic research forward. This is an exciting time to be an andrologist and, likely, a fruitful one.

Figure 1

Putative model of human zonadhesin exposure during sperm incubation under (a) non-capacitating or (b) capacitating conditions in fertile and subfertile men. Diagram indicates time course of sperm capacitation (red and blue) and zonadhesin exposure (pink and green) in fertile and subfertile men respectively. This model suggests that sperm capacitation is closely related to zonadhesin exposure in fertile men; however, a decrease of zonadhesin exposure could be associated with subfertile men related to compromised capacitation. Shaded area in (b) represents the fertilisation window.