INTRODUCTION The Ovarian Histology Core (Core B) strives to integrate the fundamental and increasingly overlapping concepts of histotechnology, molecular biology, genetics, and cell biology. Adaptations of standard and advanced histological methods and procedures have been a crucial prerequisite to producing consistent, publication quality, microscopic images of neuroendocrine and ovarian tissue samples. Over the past 5 years, the Ovarian Histology Core has provided high quality, seamless service, expertise, and collaboration, as well as rapid turn-around of high-throughput study models for the multiple investigators who participate in each project of the POI program "Hormonal Signals that Regulate Ovarian Differentiation" at Northwestern University.