Introduction

This chapter presents an overview of the cell–cell interactions at fertilization, designed to provide a context for the chapters that follow which address the diagnostic and therapeutic procedures employed in the treatment of male infertility. The many original literature citations augmented with recent references, especially to human studies, should be helpful to the reader interested in a more detailed or specific understanding of the underlying physiology and biochemistry (see Dunbar & O'Rand, 1991; and reviews by Yanagamachi, 1988; Saling, 1991; and Green, 1993).

The players and their transport

A discussion of sperm–egg interaction per se would not be appropriate without a few comments to set the stage. Successful fertilization is dependent upon the timely presence of mature gametes in the ampullary oviduct, the normal site of fertilization.

In general terms, the production of fertile sperm requires the concerted activity of the male genital tract with contributions from the testis, epididymis and accessory glands. At the testicular level, spermatogenesis, modulated by endocrine/autocrine/paracrine processes that require approximately 74 days in man, results in the production of and release to the epididymis of large numbers of differentiated sperm cells on a relatively consistent basis. Gamete production in the adult male is continuous, rather than cyclical as in the female. Spermatogenesis and its regulation are complex and poorly understood, and may be influenced by such unrelated parameters as age, scrotal temperature, diet, exercise, stress, smoking, the use of cytotoxic or recreational drugs, toxicant exposure and viral infection.