To understand the range of male infertility conditions, knowledge of normal male anatomy and its embryology is essential. This chapter will review the major developmental events from fertilization to organization of the germ layers into organ systems. It will review in depth the formation of the male genitourinary system and external genitalia. By laying a strong foundation in embryology and anatomy, providers will have a more thorough understanding of disease states.

Successful transportation of sperm from their origin within the seminiferous tubules of the testis to their site of emission in the posterior urethra involves a completely patent ductal system. Emerging from the testis into the efferent ducts, sperm enter 6–7 m of the coiled epididymal tubule, which develops into the convoluted vas deferens. The convoluted vas then gradually straightens as it courses up the scrotum, progressing first through the external ring of the inguinal canal, before diving into the retroperitoneum via the internal inguinal ring. Sperm within the vas will ultimately fill the widened ampulla of the vas and join with the seminal vesicle (SV) duct (approximately 2 cm in length) to form the ejaculatory duct (ED) that courses through the prostate. Obstruction can occur anywhere along this ductal system. This chapter will focus on the three most common sites of obstruction: the ED; the vas deferens; and the epididymis. The discussion will begin distally at the ED and progress proximally towards the testis.

Medical treatment of male infertility can be divided into two categories – targeted therapy to a known cause of infertility and empirical treatment. The most common reason to use targeted therapy is to treat hypoandrogenism. Primary hypoandrogenism (steroidogenic dysfunction) is defined as a low serum testosterone level with compensatory elevated luteinizing hormone (LH) level. Secondary hypoandrogenism (pituitary dysfunction) can be categorized further into congenital forms, such as idiopathic hypogonadotropic hypoandrogenism, or acquired forms and is characterized by low serum testosterone level associated with a low LH level relative to serum testosterone level. Other medical indications for targeted therapy are infections, inflammation, antisperm antibodies, and retrograde ejaculation, all of which are discussed elsewhere in this book. Empirical treatment is defined as treatment that relies on experience or observation alone, without due regard for system and theory, and it is routinely used in the treatment of males with idiopathic infertility or with an uncorrectable cause of their infertility.

The last and fourth edition of Infertility in the Male was published in 2009, and significant advances were realized in reproductive medicine and surgery in the intervening decade. In this edition, we have covered the more recent advances in the field while maintaining the core foundation of information needed for practitioners in diagnosing and treating the man seeking care for fertility. We have also endeavored to make the book more structured, and hopefully easier to use, for the student and specialist alike.