Departments of Pathology and Obstetrics-Gynecology and Reproductive Science, The Mount Sinai-NYU Medical Center, New York, New York Correspondence: Liane Deligdisch, M.D., Mount Sinai Medical Center, Department of Pathology, One Gustave Levy Place, New York, NY 10029. The endometrial tissue is a sensitive target for steroid sex hormones and is able to modify its structural characteristics with promptness and versatility.To ensure a maximum amount of tissue for morphological reading, the specimen should be placed on a piece of lens paper or some other adhesive tissue and then immersed in the fixative.By this means, all of the tissue fragments remain tightly attached to the lens paper, rather than floating in the fixative, and no tissue will be lost for histologic examination.Steroid hormone control of endometrial, epithelial, stromal, and presumably endothelial cells is mediated by estrogen receptors and progesterone receptors. They have high affinity to bind estradiol and progesterone, respectively.These steroid receptors are specific proteins concentrated exclusively in the nuclei of both endometrial epithelial and stromal cells, as well as the endothelial cells of stromal capillaries. This chapter contains a review of the technical procedures for handling endometrial tissues and a discussion of the morphologic aspects of the endometrium, focusing on the interpretation and understanding of the physiomorphology of the endometrial cycle.Glands : They are enlarged and dilated, with convolutions and are lined by columnar epithelium.

Ovulation induction therapy accelerates the maturation of the stroma and is often associated with a discrepancy between early secretory glands and an edematous or decidualized stroma with spiral arterioles.Morphologically, the endometrium is one of the most dynamic target tissues in women.Its cyclic structural changes mirror changes in metabolic functions, and both are regulated by ovarian estradiol and progesterone. Schematic representation of steroid hormone-morphologic interactions during the endometrial cycle.The vacuoles will be supranuclear in midsecretary phase.In the late secretary phase, the glands are saw toothed and serrated with luminal secretions Stroma: the stromal cells which were spindle shaped in proliferative cells, are now enlarged.they are round to polygonal with vesicular nuclei and abundant eosinophilic cytoplasm.This is called predecidual change as these are the precursors of decidual cells in pregnancy.