Heterogeneity of Basal Keratinocytes: Nonrandom Distribution of Thymidine-Labeled Basal Cells in Confluent Cultures Is Not a Technical Artifact

Basal surface autoradiography of [3H]dThd-labeled, confluent, keratinocyte cultures reveals that proliferating cells have a nonrandom, patterned distribution. Unlabeled cells, likewise, appear nonrandomly in clusters. We show here that failure to detect DNA synthesis in some basal cells in culture is not an artifact caused either by physical separation of the labeled nuclei from the radiographic emulsion or by a diffusion barrier that would prevent [3H]dThd from reaching basal cells.