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Editorial |
Whether you evaluate sperm every day, or read about it in the context of your work, or have been a patient yourself, you know that we generally consider sperm concentration and seminal volume the most fundamental indicators of semen quality. They are always reported first, and then used to calculate total sperm per ejaculate. Once sperm are enumerated, then we look at their motion and morphology, and hopefully at other features such as DNA or chromatin damage, and the proteins and enzymes that we think are necessary for fertility. Sperm concentration has been used the longest to assess male fertility in the clinical context. It has been evaluated and re-evaluated across time to ask a much debated question of global concern, "Is sperm concentration declining due to contaminants in our environment?" We assume that sperm concentration means something.
Dr Rupert Amann asks us to question this underlying assumption in a series of three articles in this issue of Journal of Andrology. In the "must read" perspectives piece, Dr Amann sets the stage for the resourceful review article and original research paper that follow. "Evaluating Spermatogenesis Using Semen: The Biology of Emission Tells Why Reporting Total Sperm per Sample Is Important, and Why Reporting Only Number of Sperm per Milliliter Is Irrational." Pay attention to the last word, "irrational." It was chosen carefully and is defended rigorously in the papers that follow. Dr Amann is encouraging, if not provoking, us to question our fundamental assumptions by considering the totality of male reproductive function. He puts sperm concentration and sperm number into the context of the entire reproductive tract and how it operates. He builds a scientific case for what sperm concentration means, and what it does not mean. He teaches that it is total sperm number that provides a valid indication of testis health, especially if expressed as a rate factor (sperm per hour of sexual abstinence).
Next, "Considerations in Evaluating Human Spermatogenesis on the Basis of Total Sperm per Ejaculate" provides a comprehensive and insightful review of the literature and serves as a valuable resource for students and practicing clinicians and epidemiologists alike. Here Dr Amann considers the posttesticular factors that contribute to the number of sperm ejaculated and cloud its meaning. He explains the logic of expressing sperm production as a rate factor and teaches how total sperm per ejaculate per hour of abstinence is a truer indicator of testis health than conventionally reported seminal attributes. This concept also is captured in the cover graphic.
Finally, Dr Amann and his colleague Phillip Chapman provide an original article using retrospective data mining and analysis of multiple samples from individual men. In "Total Sperm per Ejaculate of Men: Obtaining a Meaningful Value or a Mean Value with Appropriate Precision," they demonstrate how the inherently large intraindividual variability in total sperm per ejaculate dictates the number of samples needed to reliably represent testis function for individuals as well as for groups of men recruited for epidemiology studies. The article and graphic that graces the cover of this issue provide a model for determining the optimal abstinence interval to use.
As an editor, I very much appreciate the thought and care that Drs Amann and Chapman have put into this series of articles. I hope you will read, enjoy, and use the insights and information they offer. Challenging assumptions is prerequisite for changing practice. Questioning our fundamental assumptions can lead to new insights, so we welcome reactions to these articles that we suspect will stimulate healthy scientific debate.
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