Ultrastructure of Adult Epidermal Cells in Monolayer Culture

SUMMARY.— Epithelial cells from adult guinea‐pig and human skin were grown in monolayer culture and studied by phase contrast and electron microscopy. Significant differences were found between cells in vivo and in vitro. Keratinocytes show a selective dedifferentiation. They retain the ability to make desmosomes, but interdigitation is reduced and the system of tono‐filaments is disorganized. Mitochondria become long and even branched‐while microtubules become prominent, as do lysosomes and fat droplets. Ribosomes often become arranged in polyribosomes. and channels appear in the nucleus. Melanocytes showed similar changes, and 1 produced a cilium. Such changes should be taken into consideration when cells in dispersed culture are used experimentally.