ENDOMETRIAL GLANDULAR EPITHELIAL CELL PLASTICITY DURING POSTPARTUM REGENERATION AND ESTROUS CYCLICITY

A groundbreaking study has uncovered the plasticity of glandular epithelial (GE) cells during postpartum regeneration and estrous cyclicality in mice. Researchers employed a specialized mouse model with a fluorescent marker (Pgrmc2-3XFlag) and a genetic modification (Prss29-Cre) to investigate the role of GE cells in repairing the endometrial lining (LE) after childbirth and aging. The findings indicate that GE cells are not merely passive components but actively participate in LE regeneration.

Control and reporter mice were mated, and postpartum tissues were collected at various intervals. While the number of glands remained constant, FLAG-positive GE cells were found within the GE and at junctions where GE cells transitioned to LE cells. These transitioning cells exhibited both GE and LE characteristics, suggesting a flexible nature of GE cells.

Postpartum, the number of GE-derived LE cells in islands decreased slightly over time but increased again by seven weeks, indicating a proliferative expansion of these cells. This proliferation was particularly notable in older mice, highlighting their adaptive capacity during the estrous cycle.

Moreover, GE-LE junctional points were observed in older, nulliparous mice during diestrus (non-reproductive phase), further underscoring the adaptive nature of GE cells. These findings challenge the notion that GE cells are terminally differentiated, instead proposing that they maintain a stable glandular function while being capable of dedifferentiating and reprogramming into LE cells when needed.

This dynamic capability highlights the role of GE cells in both postpartum involution and normal LE cell turnover during the estrous cycle, providing valuable insights into the intricate mechanisms of uterine regeneration.