The date of the menstrual cycle can be estimated from the histologic appearance of the endometrium.


Proliferative Phase:

(1) features: pseudostratified epithelium with mitoses and no vacuoles

(2) early: glands straight

(3) mid: glands coiled and stromal edema

(4) late: glands coiled without subnuclear vacuoles in epithelium


Interval Phase (post-ovulatory day 1):

(1) features: uniform subnuclear vacuoles present in < 50% of cells


Early Secretory Phase:

(1) features: vacuolated endometrium

(2) post-ovulatory day (POD) 2: subnuclear vacuolization uniformly present ( > 50% of glands) with mitotic figures frequent

(3) post-ovulatory day (POD) 3: subnuclear vacuoles and nuclei uniformly aligned, with scattered mitotic figures

(4) post-ovulatory day (POD) 4: vacuoles assume luminal position with mitotic figures rare

(5) post-ovulatory day (POD) 5: vacuoles infrequent with secretion in lumen of gland


Mid-Secretory Phase:

(1) features: nonvacuolated endometrium with stromal edema

(2) post-ovulatory day (POD) 6: luminal secretion prominent

(3) post-ovulatory day (POD) 7: beginning of stromal edema

(4) post-ovulatory day (POD) 8: maximal stromal edema


Late-Secretory Phase:

(1) features: nonvacuolated endometrium with stromal precidualization but no stromal breakdown

(2) post-ovulatory day (POD) 9: spiral arteries first prominent

(3) post-ovulatory day (POD) 10: thick periarterial cuff of predecidua

(4) post-ovulatory day (POD) 11: islands of predecidua in superficial compactum

(5) post-ovulatory day (POD) 12: beginning coalescence of islands of predecidua

(6) post-ovulatory day (POD) 13: confluence of surface islands of predecidua, with prominent stromal granulocytes

(7) post-ovulatory day (POD) 14: extravasation of red cells in stroma, with prominent stromal granulocytes


Menstrual Phase:

(1) features: crumbling of the stroma, hemorrhage, intravascular fibrin thrombi, stromal granulocytes prominent

(2) late menstrual: regenerative changes prominent



• The secretory phase is usually reported as a 2 day range.

• Post-menopausal change can result in weakly proliferative or inactive endometrium.

• Glandular and stromal breakdown with the endometrium showing a proliferative phase can occur in estrogen breakthrough bleeding.

• Disordered proliferative phase endometrium can show a variation in gland luminal diameters.

• In hyperplasias and endometrial carcinomas more complex abnormalities of the endometrium occur.


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