Figure 2.

Premature chromosome condensation in lymphocytes and fibroblasts. a, Chromosome preparation from PHA-stimulated 72-h lymphocyte culture harvested without prior colcemid treatment. b, Chromosomes in prophase nuclei of a fibroblast line, showing an intact nuclear membrane, as observed in most of the prophase-like cells. c and d, Normal alignment of the chromosomes in metaphase plates from fibroblasts. e, Normal anaphase lagging in the fibroblasts harvested without prior colcemid treatment. f, Normal segregation of homologous chromosomes in lymphoblast cells analyzed after blocking of the cytokinesis with cytochalasin and subsequent FISH performed with two centromeric probes from chromosome 8 and chromosome 18. g, Two cells after Hoechst staining of the prematurely condensed chromosomes (arrows). h, The same cells after indirect immunostaining with lamin B antibodies, demonstrating the intact nuclear membrane.