Final answer:
The interaction necessary for tumor development is signaling, which plays a critical role in cell communication during tissue development and is also involved in the progression of tumors.
Step-by-step explanation:
The interaction between tumor cells and stromal cells that is necessary for the development of a tumor is signaling. During embryogenesis and the development of tissues, cells communicate with each other through chemical signaling and direct contact. This communication is crucial for processes such as migration, attachment, and differentiation, where cells respond to cues like fibronectin by signaling for the appropriate formation of cell junctions and tissue differentiation.
In the context of tumor development, this signaling between tumor cells and the surrounding stromal cells, which includes fibroblasts, immune cells, and the ECM, leads to the progression and growth of the tumor. This process is facilitated by a variety of signaling molecules and pathways that modulate the behavior of both the tumor cells and the stromal cells.