Occurrence of Positive Vaginal Smears in Spayed Mice. ∗

Abstract

We 1 reported that spayed mice painted with 1:2:5:6 dibenzanthracene had positive vaginal smears sporadically. In preparing to repeat this experiment we 2 found that effective amounts of estrone may be transmitted from animal to animal. The animals used in this experiment were kept segregated as a group throughout the experiment. They were spayed. No accessory ovaries were found at autopsy. Smears were made twice daily for 5 days before treatment was begun; and they were all negative. Smears were omitted until 11 weeks after treatment began, to avoid pseudo-estrus 3 effects from mechanical stimulation of the vagina. Smears were made twice a week throughout the rest of the experiment, which terminated 41 weeks after treatment with 1:2:5:6 dibenzanthracene was begun. If a positive or plus-minus smear was found all animals were smeared daily until there was a return to negative. Two untreated spayed controls were kept in the box with the treated mice. Later 4 old spayed females with uterine implants of dibenzanthracene were segregated and kept as additional controls. They were caged separately. Table I shows the positive vaginal smears. Periods when all were negative or plus-minus are omitted for brevity. Estrus was occasionally observed in the treated animals and in the controls.

Frank 4 has reported positive vaginal smears in human post-menopausal and castrate cases. Loeb 5 has reported hyperplasia of the epithelium of the cervix and vagina of old mice. These data suggest that occasional definitely positive vaginal smears develop in old or sexually involuted females. Whether the response is to local or general stimuli is unknown, as is its significance.