Characteristics of invasiveness of human nasopharyngeal carcinoma cells in organ culture, as observed by scanning electron microscopy.

Cells of a human nasopharyngeal carcinoma (CNE) were cultured in contact with embryonal mouse heart fragments wrapped in a fibrous kidney capsule as biological permeable membrane. The culture was terminated at different intervals and processed for scanning electron microscopy. Carcinoma cells showed abundant microvilli and filopodia in contact with superficial cells of the heart fragments. Cancer cells appeared firmly attached to the surface of the tissue fragments. Subsequently, malignant cells extended pseudopodia into intercellular spaces of the supporting tissue particle, and beyond the third day of cultivation, cancer cells were also found in deeper parts of the organ. The cancer cells on the surface of the specimen had apparently lost the ability to invade. After a while, microvilli and filopodia decreased in number or adhered to each other. The plasma membrane exhibited signs of degeneration.