Introduction
The endometrium is the inner lining of the uterus that plays a crucial role in the menstrual cycle and pregnancy. It consists of two main components: the
endometrial glands and the
endometrial stroma. Understanding the histological features of these components is essential for comprehending their functions and the various pathological conditions that may affect them.
Endometrial Glands
The endometrial glands are tubular structures that extend from the surface epithelium into the stroma. They vary in shape and size depending on the
phase of the menstrual cycle. During the proliferative phase, the glands appear straight and narrow, while in the secretory phase, they become more coiled and enlarged due to the influence of
progesterone.
Histologically, the glandular epithelium is composed of columnar cells that may contain cilia. These cells are responsible for secreting substances that support embryo implantation and early pregnancy. During menstruation, the functional layer of the endometrium, including the glands, is shed, and the basal layer regenerates the glands in the next cycle.
Endometrial Stroma
The endometrial stroma is a connective tissue that provides structural support to the glands and contains a rich network of blood vessels, fibroblasts, and immune cells. It undergoes significant changes during the menstrual cycle, influenced by
estrogen and progesterone. In the proliferative phase, the stroma is densely packed with fibroblasts and extracellular matrix. In the secretory phase, it becomes edematous and contains predecidual cells, which are transformed fibroblasts preparing for potential pregnancy.
Relationship Between Glands and Stroma
The interaction between the endometrial glands and stroma is vital for the normal function of the endometrium. The glands secrete factors that influence stromal cell behavior, and the stroma, in turn, supports the glands structurally and functionally. This interplay is essential for
embryo implantation and the establishment of a supportive environment for pregnancy.
Pathological Conditions
Various pathological conditions can affect the endometrial glands and stroma, leading to clinical symptoms and fertility issues.
Endometriosis involves the presence of endometrial tissue outside the uterus, causing pain and infertility.
Endometrial hyperplasia is characterized by the abnormal proliferation of endometrial glands, often due to unopposed estrogen stimulation, and can be a precursor to endometrial carcinoma.
Adenomyosis involves the invasion of endometrial tissue into the myometrium, leading to heavy menstrual bleeding and pelvic pain.
Conclusion
The endometrial glands and stroma are integral components of the endometrium, with distinct histological features and functions. Their dynamic changes during the menstrual cycle are essential for reproductive health. Understanding these components' histology is crucial for diagnosing and treating various gynecological conditions.
