**Preface XI**



Preface

Many aspects of modern life—such as industrialization, environmental pollutants, stress fac‐ tors, and poor life quality—have been blamed for declining the sperm quality and increasing the infertility rate. The alarming revelation is that infertility causes are still poorly under‐ stood, thus putting urgency to increase research effort toward male reproductive health.

Spermatozoa are derived from spermatogenesis, an orchestrated developmental process, which occurs in a continuous or seasonal fashion, depending on the species. This process is centrally governed by hypothalamic networks (i.e., kisspeptin and gonadotropin-releasing hormone (GnRH) neurons), which sustain gonadotropin discharge and gonadal steroids, and by a complex network of intratesticular cell-to-cell communications. After mitotic and meiotic divisions, spermatogonia—diploid cells—forms the round spermatids. Haploid spermatid is a round, unflagellated cell that looks nothing like the mature vertebrate sperm; to become spermatozoa, in fact, spermatids undergo extensive morphological and biochemi‐ cal transformations in the postmeiotic phase (spermiogenesis). Such a process requires the formation of acrosome and flagellum, the deep remodeling of chromatin, and the reorgani‐ zation of cytoplasmatic/cytoskeleton architecture. All these guises make spermatozoa very peculiar cells, differing from others in physiology and function. After spermiogenesis, the journey through both male and female reproductive tracts prepares the sperm to meet and bind with the egg, ensuring that an intact male genome reaches the site of fertilization.

Spermatogenesis and spermatozoa are highly sensitive to energy availability, stress, life‐ style, temperature, pollutants, heavy metals or endocrine disruptor chemicals that act at sev‐ eral levels along the hypothalamus-pituitary-gonad axis. All these aspects deeply impact critical quality parameters of semen—such as the production, motility, and/or fertilizing ability of spermatozoa—not only its genetic information but also its epigenetic blueprint. Even more worrying is that environmental-induced genetic and epigenetic damage may have transgenerational effects with an increased incidence of diseases in the next generation. Thus, the functional role of spermatozoa has been recently revised. Once considered just a "carrier" for male haploid genome during fertilization, nowadays spermatozoa store "pater‐ nal experience" and actively contribute to the embryo development and to the offspring health. Therefore, not only morphological feature, but also epigenetic signature of spermato‐

The book aims at providing basic and innovative concepts linked to sperm quality, in both physiological and pathological conditions. In particular, a part of the book addresses its at‐ tention on methods usually used in clinical practice to assess morphological parameters of

zoa, is critical to ensure their proper physiological activity.

sperm cells in infertile patients.

Chapter 11 **Advanced Label-Free Optical Methods for Spermatozoa Quality Assessment and Selection 219** Annalisa De Angelis, Maria Antonietta Ferrara, Giuseppe Coppola and Anna Chiara De Luca
