Endometrial changes during the menstrual cycle

Endometrial changes in the menstrual cycle mainly go through three phases: proliferative phase, secretory phase and menstrual phase.

1. Changes in the proliferation phase

After menstruation ends, the endometrium begins to repair and proliferate, and its thickness gradually increases. During this stage, under the influence of estrogen, endometrial glands grow and blood vessels increase to prepare for possible implantation of a fertilized egg. Typical manifestations are that the intimal thickness increases from 1-2mm to 5-7mm, and the glands become elongated and curved.

2. Changes in the secretory phase

After ovulation, the corpus luteum forms and secretes progesterone, and the endometrium enters the secretory phase. At this time, the intima is further thickened to 8-14 mm, the glands expand and secrete nutrients, and the interstitium is loose and edematous. These changes create a favorable environment for the embryo to implant, leading to the onset of menstruation if pregnancy does not occur.

3. Shedding during menstrual period

When the corpus luteum degenerates and hormone levels drop, the functional layer of the endometrium undergoes ischemic necrosis and sloughs off. It manifests as spasm and contraction of the spiral arteries, disintegration of the intimal tissue, and mixing with blood to form menstruation. This process lasts for 3-7 days, and the bleeding volume is about 20-60ml.

4. Vascular reconstruction

After the menstrual period ends, the remaining glandular epithelium in the basal layer begins to regenerate. New blood vessels grow from the basal layer to the surface. During the intimal repair process, a variety of growth factors, such as vascular endothelial growth factors, are released to promote tissue regeneration and vascular network reconstruction.

5. Hormone regulation

The entire cycle changes are precisely regulated by the hypothalamic-pituitary-ovarian axis. FSH in the follicular phase stimulates estrogen secretion, and LH in the luteal phase stimulates progesterone production. These two hormones regulate the proliferation and differentiation of intimal cells through their receptors, forming cyclic change characteristics.

It is recommended that women maintain a regular schedule and a balanced diet, and supplement iron and vitamin E appropriately. Pay attention to menstrual hygiene and avoid strenuous exercise and bathing. If you have irregular menstrual cycles, abnormal menstrual flow, or severe dysmenorrhea, you should seek medical examination promptly to rule out the possibility of endometrial polyps, adenomyosis and other diseases.