Ultrastructural characteristics of hybrids derived from normal and hand wart keratinocytes after serial passages

Somatic hybrids realized between mouse fibroblasts 3T3.4E and normal human keratinocytes or hand wart keratinocytes were examined from the 6th to the 30th passages by scanning and transmission electron microscopy. Whatever the passage, hybrid cells showed a fibroblastic morphology but, as keratinocytes, they had the capability to stratify. Branched mitochrondria were observed in hybrids whereas normal mitochondria were present in mouse fibroblasts. In human keratinocytes, most of the mitochondria were normal but sometimes few of them were branched. In wart hybrids heterogeneous nucleoli were detected instead of normal nucleoli in normal keratinocyte hybrids, 3T3.4E cells and human keratinocytes.