Objective:To explore the effect of micro RNA-24(mmu-miR-24)in endometrial stromal cells during early pregnancy in mice. Methods:Uterus tissues were collected on pregnancy of day 1

4

5

6(D1

D4

D5

D6). The expressions of mmu-miR-24 and other factors were detected by real-time quantitative PCR(q RT-PCR)

in situ hybridization

and Western blot. The primary stromal cells were induced by estradiol(E2)and progesterone(P4)for decidulization. Flow cytometry was implemented to detect cell cycle and cell apoptosis. Results:The expression of mmu-miR-24 was detected in uterine luminal

glandular epithelium

and stromal cell on Day 4. The expression level of mmu-miR-24 on D5 IS was higher than the level on D5 IIS. On D5 IS and D6 IS

mmu-miR-24 was located in decidual zone. When mmu-miR-24 mimics being incorporated into stromal cells

the number of stromal cells in the S phase was decreased

the expression of PCNA was decreased

the total apoptotic cell was increased

and the expression of BAX was increased. In contrast

when mmu-miR-24 inhibitor being incorporated into stromal cells

the number of stromal cells in G1 phase and S phase were decreased and increased respectively

and PCNA expression level was increased

the number of non-viable apoptotic cell was decreased

and BAX level was decreased in stormal cells. On the other hand

when incorporating mmu-miR-24 mimics into the decidual cells

the number of decidual cells in the S phase was decreased

and PCNA expression level was decreased

the number of non-viable apoptotic cell was increased

and BAX level was increased in decidual cells. Lastly

when treating decidual cells with mmu-miR-24 inhibitor

the number of decidual cells in the S phase was increased

and PCNA expression level was increased

the number of non-viable apoptotic cell was decreased

and BAX level was decreased in decidual cells. Conclusion:The low expression of mmu-miR-24 in stromal cells may promote the progress of cell proliferation. The high expression of mmu-miR-24 in decidual cells may promote the progress of cell apoptosis during decidulization.