Explain how progesterone produced by the corpus luteum modifies the endometrial lining to make it receptive for embryo implantation. Include the cellular and molecular changes involved.
Answer
Progesterone transforms the endometrium from a proliferative to a secretory phase, stimulating stromal cell decidualization, glandular secretion, vascular permeability, and upregulation of adhesion molecules to facilitate implantation.
Step-by-step solution
- During the luteal phase, the corpus luteum secretes .
- binds to nuclear progesterone receptors in endometrial epithelial and stromal cells.
- This initiates a shift from a proliferative to a secretory phenotype, leading to increased synthesis of glycogen and proteins in glandular cells.
- Stromal cells undergo decidualization: they enlarge, accumulate lipid droplets, and produce cytokines like IL‑1 and IL‑6.
- also enhances vascular permeability by upregulating endothelial adhesion molecules (e.g., ICAM‑1) and angiogenic factors.
- Together these changes create a receptive environment that allows blastocyst attachment and invasion.
Common mistake: Neglecting the role of decidualization in implantation
Concept tested: Endometrial receptivity
Published · How this solution was prepared and checked
← All Human Reproduction questions