Microvascular architecture of the mechanically induced hydrosalpinx in the rabbit

This study was undertaken to document changes in microvascular architecture (MVA) associated with the mechanically induced rabbit hydrosalpinx. Twelve adult female virgin rabbits underwent isthmic and ampullary occlusion at laparotomy, with small tantalum clips. Two or four weeks later, methylmethacrylate vascular casts of the mechanically induced hydrosalpinges were prepared and examined by scanning electron microscopy. This revealed plicae of markedly reduced size projecting into the distended lumen and fewer subepithelial capillaries were cast in the interplical region than in the adjacent plicae. The fluid accumulation in the hydrosalpinx is presumably a net transudate of the tubal subepithelial capillary bed. The large ampullary plical veins seen in controls were absent; the prominent isthmic arteries normally observed were more pronounced and their branching was more extensive. Subserosal veins were more distended over the hydrosalpinx than in adjacent normal isthmus or ampulla. These observations indicate that the major vascular effects of hydrosaplinx formation are an alteration of interplical MVA and subserosal venous dilation, and suggest higher vascular pressure and blood flow in the mechanically induced hydrosalpinx. We speculate that this implies greater epithelial transudation and that maintenance of the hydrosalpinx, in this model, is probably due to microvascular alterations.