Several possible sources of TDs (IMAGE) Science China Press Caption a: Tumor cells break through the lymph node envelope; b: Tumor seeding; c: Tumor cells breaking through blood vessels; d: Lymph nodes replaced by tumor cells; e: Discontinuous extension of the tumor. (Created with BioRender.com). Credit ©Science China Press Usage Restrictions Use with credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.