From the Guidelines
Secretory endometrium refers to the phase of the uterine lining that occurs after ovulation during the second half of the menstrual cycle, characterized by thickening and development of secretory glands in preparation for potential implantation of a fertilized egg, as described in studies such as 1. This phase is crucial for embryo implantation and is triggered by progesterone produced by the corpus luteum in the ovary. The secretory endometrium is marked by glands that become more coiled and filled with glycogen and other nutrients, increased blood supply through spiral arteries, and stromal cells that become more swollen and edematous. Some key features of secretory endometrium include:
- Thickening of the uterine lining
- Development of secretory glands
- Increased blood supply through spiral arteries
- Stromal cells becoming more swollen and edematous These changes create an optimal environment for embryo implantation by providing nourishment and support, as noted in research on human endometrium 1. If pregnancy does not occur, progesterone levels fall, leading to breakdown and shedding of this secretory endometrium during menstruation. Identification of secretory endometrium in tissue samples can help healthcare providers determine where a woman is in her menstrual cycle and assess for normal hormonal function, which is important in evaluating fertility issues or abnormal uterine bleeding, as discussed in the context of hormonal replacement therapy 1.
From the Research
Definition of Secretory Endometrium
- The secretory endometrium refers to the phase of the menstrual cycle where the endometrium is preparing for a potential pregnancy, characterized by secretory changes in response to progesterone 2, 3.
- During this phase, the endometrium undergoes changes to become receptive to implantation of a fertilized egg, including an increase in glandular secretions and a decidual reaction in the stroma 4, 5.
Characteristics of Secretory Endometrium
- The secretory endometrium is typically characterized by the presence of subnuclear vacuoles, decidual reaction, and squamoid "morules" 5.
- Morphometric analysis of epithelial cell nuclei has shown that the nuclei in the secretory endometrium are elongated and hyperchromatic, with reduced expression of estrogen and progesterone receptors 6.
- The secretory endometrium can be affected by various factors, including hormonal therapy, which can induce a range of histologic changes, including secretory hyperplasia and decidual transformation 4, 5.
Clinical Significance of Secretory Endometrium
- Abnormalities in the secretory endometrium, such as a deficient secretory phase, can be associated with menstrual irregularities and infertility 6.
- Secretory changes in the endometrium can also be seen in response to progesterone therapy for endometrial hyperplasia and neoplasia, and do not rule out residual carcinoma 5.
- Understanding the physiology and pathophysiology of the secretory endometrium is essential for optimizing patient management and developing effective treatments for abnormal uterine bleeding and other menstrual disorders 3.