A chronic infiltration of polymorphonuclear leukocytes was invariably found in the infertile regions of uteri containing foreign bodies in conventional rats, germfree rats, mice, and rabbits. Polymorphonuclear leukocytes were never found in the fertile regions of these uteri.
A foreign body in the uterus of the rat, and probably also the mouse, was associated with a bacterial infection which spread the inflammatory response throughout the horn containing the foreign body, and in the mouse occasionally into the control horn as well. No bacteria could be cultured from the rabbit uterine horn containing a foreign body.
In the germfree rat, both the infiltration of polymorphonuclear leukocytes into the uterus and fertility were significantly different from that observed in the conventional rat. Whereas in the conventional rat the inflammation and infertility extended along the entire length of the uterine horn containing a small foreign body, in the germfree rat the inflammation and infertility were closely correlated to the position of the foreign body.
As judged by measurements of lysozyme in the uterine lumens of rats and rabbits, polymorphonuclear leukocytes released their contents into solution in the uterine lumen. It is concluded that some substance derived from polymorphonuclear leukocytes may exert toxic effects on fertilized ova or on spermatozoa and thus be responsible for the infertility of uteri containing foreign bodies.