Andrology is the discipline that corresponds to gynecology for men, but while the latter is a well-established discipline, the former is still an emerging field. A simple definition of andrology will include the study of all subjects that may affect the male reproductive system. In the last years, a striking large number of topics has emerged in this field and there is an increasing amount of information that may be useful for graduate, post-graduate and even well-established researchers. Herein, we summarize the available information so far in this area, presenting a review and a critical analysis of the available data on the most relevant subjects with interest to andrology, with emphasis on the biochemistry of the processes. This e-book is divided into 14 chapters, all coordinated by Dr. Marco G. Alves and Prof. Pedro F. Oliveira.
The first chapter is a brief introduction to the historical evolution of andrology and how biochemistry has emerged as a partner, contributing to the emerging relevance of this discipline. The second chapter describes general considerations on testis physiology, testicular anatomy and functional organization, as well as its embryonic development. The third chapter discusses the basic aspects of testicular cells physiology and function. The fourth chapter presents the basic aspects of spermatogenesis, a key event for species propagation, from a biochemical perspective. It is mainly focused on the mechanisms responsible for postnatal testis development but it also presents an overview on the complex events that control the spermatogenic cycle. Many of those changes are under the action and function of male-associated hormones that trigger signaling pathways thus, the fifth chapter is dedicated to those issues. The endocrine regulation of sexual maturation and sperm formation is still a matter of great debate and with an enormous interest. In the sixth chapter, the transition period between childhood and adulthood is discussed, particularly the biochemical changes that control pivotal events responsible for the sexual maturation of the individuals. There is also an overview on puberty-associated disorders, pinpointing the clinical features that should be taken into consideration and the deleterious signals that may occur until sexual maturation is achieved. In the seventh chapter, the biochemical events occurring in the epididymis that end-up in sperm maturation, are discussed. It also discussed the structural organization of epididymal epithelial cells and secretory proteins and their involvement on the spermatozoa modifications that occur during the process of maturation. The eighth chapter is dedicated to the formation and biochemical properties of seminal plasma and male accessory glands. Those changes are essential for spermatozoa to acquire fertility capacity. In the ninth chapter, the functional and physiological aspects of spermatozoa, as well as its epigenome are presented, which may have an enormous implication to the success of the pregnancy and latter to the offspring health. The male gamete is very dynamic and has to move, capacitate, migrate through the female tract, bind to the egg membrane and fuse to the oocyte, resulting in a viable embryo. The tenth chapter is dedicated to the sequential modifications and the molecular mechanisms that occur during the journey of spermatozoa through the female reproductive tract since they have a pivotal role in couple’s fertility success and offspring health. Those events may be compromised by several factors that compromise male reproductive health. Congenital disorders, such as hypospadias, undescended testis, testicular atrophy and testicular cancer have increased among young males and even erectile dysfunction and sexually transmitted diseases are still problems that compromise male reproductive health. These issues are discussed in chapter eleven. The twelfth chapter discusses how the pandemic incidence of metabolic diseases is contributing for the worldwide decline in both, sperm quality and male reproductive health. The biochemical changes induced by lifestyle factors and nutrition in the testis are on spotlight to unveil the mechanisms by which metabolic diseases affect nativity rates and the offspring. There is an intense debate whether worldwide sperm quality is decreasing and the factors that may be responsible for that. Environmental contaminants have arisen as main contributors to the decline on sperm quality. Thus, the molecular mechanisms by which environmental cues alter male reproductive health remain a matter of great interest and are discussed in the thirteenth chapter. The last chapter is dedicated to the biochemical changes in the reproductive function of the aging male. Later parenting is very frequent in modern societies. Nevertheless, the quality and the altered patterns of epigenetics/gene expression in aging sperm remain to be disclosed. Thus, the biochemical changes that occur in testis and sperm and that go along with aging will be on the spotlight for the next decades.
Nowadays, there is a huge investment in reproductive healthcare that is mainly applied in assisted reproductive technologies. However, the long-term effects of these treatments and the causes for male infertility are not cautioned. Overall, this book discusses all the major topics of interest for andrology and mainly presents a focus on the biochemistry of andrology without avoiding the debate on the clinical relevance of the discussed topics. This is a fast growing discipline and thus, there is a great need to educate and prepare students, scientists and physicians for the novel challenges. As scientists working in the field, we felt that most books focused on Andrology lack a strong biochemical view on the topics. As biochemists working in the field for more than a decade, we gathered our team and prepared a book that discusses a large spectrum of topics with high relevance for andrologists all over the world. This book will be valuable for all those working on andrology that aim to understand the magnificent biochemical control of the male reproductive health. Our team had great pleasure preparing this book and we are sure that it will be very useful.
Marco G. Alves
Health Sciences Research Centre (CICS-UBI),
Faculty of Health Sciences, University of Beira Interior,
Pedro F. Oliveira
Department of Microscopy, Institute of Biomedical Sciences Abel Salazar,
UMIB - Unit for Multidisciplinary Research in Biomedicine,
I3S - Institute for Innovation and Health Research,
University of Porto,