Cell ultrastructure during the development and the transformation of a pig--uterine tube cell line

Observations by electron microscopy disclosed ultrastructural features which were not apparent by light microscopy during the three stages of the development of a pig uterine tube cell line. Ciliated cells without dynein arms were found naturally occurring in the first 100 subcultures (pseudo-diploid stage). They were not observed in the routinely growing cultures after the concomitant detection of the first chromosome marker and expression of a type C virus, unless the cells were treated with estradiol (transformed stage). Gap junctions and increased numbers of lamellar and lysosomic bodies and vacuole-like structures were observed in clusters of tumoral cells in the high subcultures if a new chromosome marker occurred (malignant stage). Type C viruses were found as early as the 106th subculture (transformed stage) in populations of actively dividing cells 3 days after seeding, but not in populations of nondividing cells a week after seeding. Both viruses and viral reverse transcriptase were continuously released in the 300 subsequent subcultures.