Immunohistochemical approaches to the study of human fetal ovarian development

The development of primordial germ cells into oocytes within primordial follicles involves a complex sequence of proliferation, developmental commitment, entry and arrest in meiosis, and association with surrounding somatic cells. These processes occur over the first few months of development in the human, with multiple stages of development present at any one time point. Immunohistochemistry has been hugely instructive in identifying the various key stages in ovarian development, by allowing simultaneous visualization of different stages of germ cell development, and their spatial arrangement. These studies allow comparison with other species and have identified key differences between human and murine ovarian development as well as giving a basis for functional studies. In this chapter we describe the main methodologies used in immunohistochemistry, using both chromogen and fluorescence approaches, and both single and double antigen detection.