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Vascular Remodeling and Angiogenesis: DISCUSSION(2)


Ovarian fragments implanted intramuscularly showed much better follicular maintenance. Many follicles, from the primordial through the antral stages of development, could be found in the implant, suggesting recovery of ovarian function. At 6 days after implantation, the vasculature in the implant was very similar to that of control ovaries, with normal morphology of blood vessels. Despite this favorable outcome, necrotic regions in the medulla of the graft were detected at the first days (1-3 days) after transplantation, suggesting that early transitory necrosis may be overcome and the maintenance of the grafts improved at a later time (6-7 days). The medullar damage during the first hours after transplantation was accompanied by regression of pericytes and SMC, which was symptomatic of insufficient blood supply. generic geodon

The superior pericyte coating in the intramuscular versus the subcutaneous grafts seems to be related to the different blood supply between these two sites. The mechanism for vascular preservation in the two transplantation sites remains to be elucidated in future studies. It is possible, e.g., that the hypoxic stress and the subsequent production of factors that contribute to detachment of SMC and pericytes, such as VEGF and ANG-2, are higher at the subcutaneous site. Supplementation of stabilizing factors such as PDGF and/or ANG-1 to the graft, prior to the transplantation, in order to supply perivascular support may prevent pericyte and SMC loss and improve follicular survival also in this region. Administration of growth factors aimed to promote vascular maturation was reported previously to induce growth of stable and mature blood vessels.

Considering the fact that the procedure of ovarian transplantation will require a freezing-thawing step in which the large developing follicles will be damaged, the main goal is preservation of the pool of nongrowing small follicles. An encouraging result was the fact that the number of primordial follicles in the intramuscular grafts remained essentially unchanged during a month after transplantation.