Histopathologic changes related to fibrotic oviduct occlusion after genital tract infection of mice with Chlamydia muridarum

Objectives: We sought to determine if intraluminal occluding fibrosis of the oviduct occurs after urogenital Chlamydia muridarum infection in mice. Study: Oviduct occlusion was assessed by infusing dye into the distal uterus and tracking the diffusion of the dye into the oviduct. We also conducted histologic assessment of the affected tissues using hematoxylin and eosin (H&E) and Masson trichrome stains. Results: All previously infected susceptible mice had occluded oviducts compared with 17.5% of previously uninfected mice. Oviduct occlusion correlated with hydrosalpinx formation and infertility. Intraluminal oviduct fibrosis was observed in several sections of tissue displaying hydrosalpinx but not in tissues without hydrosalpinx. Fibrosis was localized to the oviduct isthmus and oviduct proper, proximal to the uterus. Conclusion: Intralumenal occluding fibrosis of the oviduct is a sequela of infection with C muridarum in this model. These observations support the use of the murine model to study pathogenesis of chlamydial upper genital tract infection.