Spermatogenesis -- Organization of the seminiferous epithelium -- Synchronization of spermatogenesis -- Regulation of spermatogenesis -- The Sertoli cell -- Origin and maturation of the Sertoli cell -- Altered Sertoli cell differentiation in testicular disorders -- Differentiation markers of the Sertoli cell -- Sertoli cell intercellular communication -- Knockout and transgenic mouse models and mutations in man -- The differentiation of male germ cells -- The regulation of gene expression during prespermatogenesis -- The regulation of gene expression during spermatogenesis -- Idiopathic male infertility: impaired histone-to-protamine exchange?- Male infertility caused by incorrect transcriptional regulation -- Male infertility caused by incorrect translational regulation -- Male infertility caused by incorrect chromatin condensation -- Carcinoma-in-situ of the testis and testicular germ cell tumour: impaired intercellular communication due to altered Sertoli cell differentiation?- Carcinoma-in-situ of the testis and testicular germ cell tumour -- Sertoli cell differentiation in seminiferous tubules infiltrated with carcinoma-in-situ of the testis -- Role of gap junctional intercellular communication in carcinogenesis -- Role of gap junctional intercellular communication in the development of carcinoma-in-situ of the testis to testicular germ cell tumour -- References -- Subject index.Unwanted childlessness affects approximately one in six couples worldwide. - though the exact proportion of the predominant cause of the problem remains controversial, according to the World Health Organization (WHO), in nearly 40% of cases the cause can be attributed to the female, in 20% to the male, in 25% to both, and in 15% the cause remains unknown. Based on these ?gures, the - cidence of male factor infertility in the general population is approximately 7%. The majority of these men, approximately 30%, experience irreversible idiopathic infertility and cannot father children without some form of medical intervention. Male factor infertility, in addition, may be caused by testicular germ cell cancer, which is known to represent the most common cancer among young men, aged 15 to 35 years, in Western industrialized countries. The number of affected men has increased dramatically over the past 50 years. There is now growing evidence that human testicular germ cell cancer originates from fetal germ cells exhibiting an aberrant programme of gene expression, and tumour progression may be favoured by an aberrant Sertoli cell-germ cell communication.