Semen analysis has been the standard of clinical laboratory assessment(s) of male fertility potential for more than 70 years [1–4]. Methodologies for performing the semen analysis, along with standard practices to ensure quality in clinical laboratory practices throughout testing, have been codified in multiple World Health Organization publications [5–9]. A common, and albeit disappointing, conclusion regarding the semen analysis is that the lower reference limits have limited predictive value for fertility or, for that matter, infertility (see, for example, [10–14]). A partial explanation for this inadequacy is that, with the exception of sperm motility, sperm function requirements that are necessary for successful fertilization and term delivery are not assessed in the semen analysis. This dilemma impacts the ability of clinicians to provide an evident diagnosis to the patient couple concerning the presence/absence of male subfertility, especially in the absence of genetic, hormonal, or urogenital abnormalities. This dilemma becomes further exacerbated for the clinician who must decide on an appropriate therapeutic strategy to address the infertility and for the patients who balance their desires in conjunction with spiritual, emotional, and financial considerations.

In the past decade greater emphasis has been placed on investigation of the human male gamete. As a consequence many unique and revealing characteristics have been identified; providing greater insight and understanding regarding human sperm production, maturation, and function. However, there has not been a comprehensive book on these topics published for more than 8 years. The focus of this book will be on the human and where data is lacking non-human animal species will be substituted to serve as representative example.

The composition of the spermatozoon, always regarded as critical for successful fertilization, has gained even greater significance in the events post-fertilization. The fidelity of the genome in its composition and construction are known to significantly influence fertilization, embryogenesis and live birth. Several contributions to this book elegantly detail the overt and more subtle characteristics of both the competent and dysfunctional sperm genome complex.

Historically, the spermatozoon has somewhat been viewed as a typical single cell; meaning that its membranes, organelles and metabolic activities are all connected. Emerging data clearly demonstrates the uniqueness of the spermatozoon in that discrete compartments can be identified whose physiology and biochemistry are separable. Several of the chapters herein offer intriguing revelations in this regard.

The yin and yang image that forms the central core of the micrograph on the front of this book serves as a symbolic reflection of the book's subtitle: production, maturation, fertilization, regeneration.