Accurate Identification of Experimental Pulmonary Metastases2

The accurate counting and sizing of small, lightly pigmented tumor metastases in the lungs of experimental mice have been facilitated by the development of a method whereby the lungs were insufflated with a 15 percent solution of India ink. After being washed with Fekete's solution, which is a bleach preservative, these tiny implants, not detected in the unstained fresh lung, became discretely visible. The accuracy and time-saving features of this method aid in the verification of lung metastases and permit a much wider range of spontaneous and induced animal tumors in studies of experimental tumor metastases.