Growth of free tumor cells in the pleural exudate and their implantation into the pleura of the mouse.

that pleural exudate from patients with thoracic tumors may contain free tumor cells, some of which show mitotic figures. The study of the diagnostic significance of these cells has long been a part of exfoliative cytology (1, 10). How ever, our extensive search in the literature on cancer did not reveal any mention of experiments concerning the growth potentialities of free tumor cells floating in the pleural exudate. Our previous work on the growth characteristics of free tumor cells in the peritoneal fluid (@, 3) has shown that any mouse tumor cells (Sarcoma 37, malignant lymphoma, Sarcoma 180', carcinoma in CS!! mice,' carcinoma in CAF1 mice,' melanoma in DBA mice,' etc.), inoculated into the peritoneal cavity induced an accumulation of fluid and multiplied in this medium at a high rate as free cells. Eventually, they settled in subserous con nective tissue (where the serosa was damaged by the injecting needle or by injected material) and grew into solid tissue tumors. In a new series of experiments based on the same technic and method, we have found that similar phenomena of free cell multiplication in the fluid and their localization in tissues, with subsequent tumor growth, can be obtained also in another serous cavity of the mouse†" the pleural cavity. However, the anatomical and histological structure of the pleural cavity determined some essential differ ences in growth characteristics of intrapleurally inoculated tumor cells as compared to those in the peritoneal exudate. This comparative study was found useful for analysis of experimental data re ported below.