Figure 5: HE staining of occluder at different time points after procedure (a, c, e, and g original magnification: ; b, d, f, and h original magnification ). (a, b) At 8 weeks after implantation, PDO (black arrow) and PLA (blue arrow) wire was kept in shape; there were a large number of inflammatory cells around the around PDO wire (black arrow). (c, d) At 12 weeks after implantation, the edge of PDO wire (black arrow) began to disintegrate, and newly formed microvessels could be seen (red arrow); PLA wire (blue arrow) was surrounded by inflammatory cells. (e, f) At 16 weeks after implantation, the majority of the edge of PDO has been disintegrated (black arrow); the inflammation has subsided; well remodeling microvessels could be seen (red arrow); aggregates of multinuclear giant cells (yellow arrow) were found in the areas where the PDO wires had undergone degradation. (g, h) At 24 weeks after implantation, PDO almost completes degradation and substituted by hyperplastic fibrous connective tissue (black arrow), the PLA (blue arrow) that was partly degraded and neovascular could be seen (red arrow).