I and Cherry pointed out the greatly increased frequency with which "mixed" or adenosquamous carcinoma of the cervix was seen in pregnant patients when compared with the frequency of this tumor in nonpregnant patients1-4 T h e presence of a glandular component in some of the less well differentiated cancers was established by finding mucinproducing cells in the neoplastic epithelium. They suggested that both the squamous and glandular elements in these cancers arose from epithelial cells capable of differentiating into either form, and that the greater frequency of "mixed" carcinoma in pregnancy might be the result of the hormonal stimulation associated with pregnancy. If this hypothesis is correct, then it seems reasonable that the neoplastic epithelium from cases of in situ carcinoma diagnosed during pregnancy should contain mucin-producing cells with greater frequency than similar epithelium from nonpregnant patients. T h e present study was done to investigate this point.
METHODS AND MATERIALS
Cases o E carcinoma in situ in nonpregnant patients between 1957 and 1964 were obtained from the files of the Free Hospital for Women and cases of carcinoma in situ in pregnant patients seen between 1959 and 1964 were obtained from the files of the Boston Lying-in Hospital. T h e slides in each case were reviewed, and representative sections were set aside for further study. The corresponding