DNA replication patterns of human chromosomes from fibroblasts and amniotic fluid cells revealed by a Giemsa staining technique.

A technique is described for visualizing late-replicating regions by a Hoechst 33258-Geimsa-staining procedure combining the techniques of Latt (1973) and of Perry and Wolff (1974). The advantages are two-fold: distinct bands are obtained and many possible mistakes and interpretation difficulties with autoradiography are avoided. The time sequence of late-replication patterns (excepting C-group chromosomes) has been established in human fibroblasts of adults, and these results have been compared with three of four different cell types from amniotic fluid. No significant differences in late-replication patterns and time sequence of the different cells could be discovered. As expected, the replication patterns are in good concordance with the patterns of G- and Q-bands. Some exceptions are described.