Endometrial glands are tiny tube-shaped structures that make up part of the endometrium, the inner lining of the uterus. The glands are made of epithelial cells that produce mucus and other fluids to help prepare the uterus for pregnancy. The spaces between the glands are filled with a supporting tissue called the stroma, which contains blood vessels and immune cells.
Endometrial glands are a normal part of the body. Pathologists describe them frequently because their size, shape, number, and appearance change in predictable ways with hormones and with age. Those changes give important information about hormone balance, where a person is in the menstrual cycle, and whether an abnormal growth is present. This article explains what endometrial glands do, how they normally change, and what it means when a report describes them.
What do endometrial glands do?
The main job of the endometrial glands is to produce secretions that nourish and protect an early embryo, and to help create the right conditions for a fertilized egg to implant in the uterus. Because this role depends on hormones, the activity of the glands changes throughout the menstrual cycle:
- Proliferative phase — In the first half of the cycle, the glands grow and lengthen under the influence of estrogen.
- Secretory phase — After ovulation, the glands become wider and begin to produce and release nutrients under the influence of progesterone.
- Menstrual phase — If pregnancy does not occur, hormone levels drop, the glands stop secreting, and the upper layer of the endometrium is shed during menstruation.
After menopause, hormone levels fall permanently and the endometrial glands become small and inactive. This is a normal change with age, not a disease.
What do endometrial glands look like under the microscope?
Under the microscope, endometrial glands appear as rounded or elongated spaces lined by a single layer of epithelial cells. Their appearance changes with the stage of the menstrual cycle, which is why pathologists can often tell where a person is in their cycle just by looking at the tissue:
- Proliferative phase — The glands are narrow, straight, and closely packed, and the cells have small, uniform nuclei.
- Secretory phase — The glands become wider and more coiled, and the cells contain clear material (glycogen and mucus) that they release into the gland to nourish a possible embryo.
- Menstrual phase — The glands break down and are shed along with the surrounding tissue and blood.
- After menopause — The glands are small, widely spaced, and inactive.
What conditions affect endometrial glands?
Many conditions of the uterus involve changes in the number, size, or appearance of the endometrial glands. Common examples include:
- Endometrial hyperplasia — The glands become crowded and more numerous, making the endometrium thicker than usual. This is usually the result of long-term estrogen stimulation.
- Endometrial polyp — A localized overgrowth of glands and stroma forms a polyp, which may cause bleeding.
- Disordered proliferative endometrium — The glands vary in size and shape more than expected, but are not crowded enough to be called hyperplasia.
- Atrophic endometrium — After menopause, the glands become small and inactive because hormone levels are low. This is a common cause of bleeding after menopause.
- Chronic endometritis — Long-lasting inflammation of the endometrium, in which immune cells are found around the glands.
- Endometriosis — Endometrial glands and stroma are found outside the uterus, where they can cause pain and scarring.
- Endometrial carcinoma — The gland cells become cancerous and grow without normal control. The most common type, endometrioid carcinoma, forms glands that resemble abnormal endometrial glands.
Pathologists assess the shape, size, spacing, and cellular appearance of the endometrial glands to decide whether the changes are normal for a person’s age and cycle, hormone-related, or caused by disease.
Why are endometrial glands important in a pathology report?
Pathologists often describe endometrial glands when reporting the results of an endometrial biopsy, because the appearance of the glands provides clues about hormone balance, the phase of the menstrual cycle, and whether an abnormal growth is present. Two features matter most: how crowded the glands are, and whether the cells lining them show atypia, meaning they look abnormal.
Crowded glands without atypia support a diagnosis of hyperplasia without atypia, which carries a relatively low risk of developing into cancer. Crowded glands with atypia indicate a precancerous condition called atypical hyperplasia, also known as endometrioid intraepithelial neoplasia (EIN). These are two names for the same diagnosis, and your report may use either one. This condition carries a higher risk of progressing to endometrial cancer and is usually treated.
The glands are also assessed in relation to a person’s age and symptoms. For example, glands that look active in a person who has gone through menopause may prompt further evaluation, because the glands would normally be inactive at that stage. Together, these observations help doctors identify the cause of abnormal uterine bleeding and choose the right treatment.
Questions to ask your doctor
- What did my report say about my endometrial glands?
- Are the glands normal for my age and where I am in my menstrual cycle?
- Did the report mention crowding, hyperplasia, or atypia?
- If atypia was found, does that mean I have a precancerous condition?
- What do these findings mean for my risk of endometrial cancer?
- Could my findings explain my abnormal bleeding?
- Do the findings suggest a hormone imbalance that should be treated?
- Will I need additional testing, treatment, or follow-up biopsies?
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