The expression of the proapoptotic Bax may change the anti apoptotic consequences of Bcl 2 and promote cell death. Moreover, the increased levels of active caspase 9 may also be linked with Bax/Bcl 2 and Bcl xL phrase, suggesting the mitochondrion dependent signalling pathway is required in regression throughout pregnancy progression. From days 8 to 10 of gestation, Bcl 2, Bax and Bcl xL phrase were especially intense in-the principal decidual zone extending buy Doxorubicin afterwards to all the antimesometrial decidua, disappearing thereafter. These results are linked to our previous findings that showed expression of active caspase 3 and suggested that this place regresses from the initiation of an apoptotic process. The mesometrial decidua is formed during this period reaching its maximum devel-opment on day 12, regressing a short while later. At the same time occurs the attack of the maternal arteries by the endotrophoblasts. Our results suggest that the expression of Bax and active caspase 3 in the smooth muscle cells of some arteries was also seen in other vascular internet sites at which the smooth muscle cells endure apoptosis under regulation of Bcl 2 family proteins. Moreover, throughout the devel-opment of the mesometrial decidua the non decidualized cells Plastid didn’t convey any of the apoptogenic factors examined. After decidualization has happened the cells show Bcl 2, each of the elements, Bcl xL and Bax. These results support the notion that the death repressor activity of Bcl2 and Bcl xL is very important in promoting the success of the mesometrial decidua till its utmost development and when the expression of Bax becomes prevalent, this results in the death of the decidua that progressively reduces to a thin layer of cells. Nevertheless, the level of undifferentiated cells near to the circular muscle coat didn’t convey the members of the Bcl 2 family examined during pregnancy, hence, possibly maintaining a progenitor citizenry of cells where precursor cells differentiate into mesometrial decidual cells. In-fact, in previous studies we noticed dub assay that within the mesometrial area near the myometrium layer, some decidual cells and low decidualized stromal expressed high degrees of the proliferating cell nuclear antigen, and the mitotic factor insulin like growth factor I. Moreover, inside the human uterus, myofibroblasts are present at the endometriomyometrial junction and a steroid hor-mone dependent metaplasia of stromal cells into myocytes does occur in this zone suggesting that junctional zone myocytes are directly linked to endometrial stromal cells. One interesting observation was the high degrees of Bax in the circular muscle layer of the mesometrial rod compared to the discoloration observed for the two anti apoptotic factors.