Abstract
Macrophages of endocrine organs have been identified by immunohistochemical localization of the macrophage-specific antigen F4/80. F4/80+ cells line vascular sinuses and capillaries in anterior and posterior pituitary, adrenal cortex, corpus luteum, parathyroid, pineal gland, and islets of Langerhans. In testis approximately 20% of interstitial cells are F4/80+. F4/80+ cells infiltrate corpus luteum in increased numbers during luteolysis.