Abstract
Mice and rabbits receiving large doses of estrogens develop pyometra. 1 2 3 4 5 6 Estrogenic hormones may induce physiological changes favoring a leucocytic invasion of genital tissues. 2 3 4 It has been suggested that this inflammatory condition may be related to the leucocytic infiltration occurring during normal post-estrus. We have tried to determine whether bacteria are present in the uteri of normal mice and whether estrogenic hormones induce changes resulting in bacterial invasion of the uterus.
Mice from several strains and of varying ages were used. All that were treated with estrogens (hydroxyestrin benzoate) were young, sexually mature, virgin females. The estrogen, in oily solution, was injected subcutaneously, usually in a single dose of 500 I.U. (1/20 cc). The mice were killed after intervals of 2, 4, 7, 10, 14, and 15 days following the initial injection (Table II). Bacteriological studies were made on the uteri of immature, mature virgin, multiparous and castrated females; of mice receiving injections of oil alone and of the blood of injected and untreated mice (Table I). In a third series one uterine horn was cut from the cervix and the cut end fixed to the abdominal wall. One month later 500 I.U. of estrogen were injected subcutaneously and 7 days later bacteriological examination of the ligated and intact horns was made.
The mice were kilIed with illuminating gas and opened under aseptic conditions. The uterine horns were removed well above the cervix, ground in 0.5 cc. sterile saline and one loopful of the resulting suspension was streaked on heart-infusion blood agar and another inoculated into heart-infusion broth. Growth, if any, appeared in 12 to 24 hours. Negative cultures were examined for 5 days. Frequently colonies growing on the plates were subcultured and identified.
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