Fallopian tubal mucosal damage induced experimentally by Escherichia coli in the rabbit. A scanning electron microscopic study.

Pelvic inflammatory disease is the main cause of infertility due to a tubal factor. The importance of Gramnegative bacteria as major infecting organisms in pelvic inflammatory disease has been recently recognized. The predominant facultative pathogen found in tuboperitoneal fluid from women with salpingitis are coliform bacteria. This study describes an animal model for E. coli mediated tubal mucosa damage. E. coli (10(5)-10(9) bacteria 1 ml) was injected into the right Fallopian tube of sixty rabbits; the left tube injected with culture medium, served as a control. The luminal surface of the oviducts was examined by scanning electron microscope at various intervals after the injection. The degree of damage was found to be dose-dependent and maximal seven days after innoculation. The injury comprised of large areas of deciliation, severely shortened cilia, swollen and adherent throughout their entire length and disappearance of microvilli from the secretory cells. A process of regeneration began two weeks after the innoculation and was completed eight weeks later. Fertility studies carried out after completion of regeneration showed no difference in the ratio of corpora lutea/gestational sacs between the treated and control sides of individual pregnant animals. This model sheds light on the pathogenesis of tubal surface injury by E. coli and suggests that the major effects described are mediated through the endotoxin liberated from the cell wall of these bacteria and that, therefore, antibiotic treatment has no effect on the magnitude of injury. Endosalpingeal regeneration correlates well in this animal model with normal fertility suggesting that morphologic integrity of the surface epithelium may be a good criterion in assessing the reproductive capacity of the fallopian tube.