Overview
Introduction
The endometrium is the inner mucous lining of the uterine cavity and one of the most dynamic tissues in the body, remodeling itself completely with each menstrual cycle.
The endometrium is the inner mucous lining of the uterine cavity and one of the most dynamic tissues in the body, remodeling itself completely with each menstrual cycle. It is organized into two layers: a functional layer, which thickens, secretes, and is shed during menstruation, and a basal layer, which is retained and regenerates the functional layer each cycle. These changes are orchestrated by the cyclical rise and fall of estrogen and progesterone. Under estrogen in the proliferative phase, the endometrium regrows and thickens; under progesterone in the secretory phase, its glands become glycogen-rich and the lining becomes receptive to a blastocyst during a brief implantation window. If implantation occurs, progesterone transforms the endometrium into the decidua, the specialized maternal tissue that anchors and supports the developing placenta. Why this matters clinically: For the maternal-newborn nurse, the endometrium is central to understanding fertility, early pregnancy, and several important complications. The receptive secretory endometrium enables implantation, and inadequate transformation contributes to infertility and early loss. After birth or pregnancy loss, the endometrium is vulnerable to infection, and postpartum endometritis is the...
