High resolution replication patterns of the human Y chromosome. Intra- and interindividual variation

Replication studies on prophasic human Y chromosomes reveal 4 early replicating segments in the euchromatic portion. The distal segment of Yp replicates first. After replication of the euchromatic part is almost finished 3 to 5 segments start replication in the heterochromatic portion of Yq. These segments exhibit considerable intraindividual variation with respect to the origin of onset of replication. While the location of these bands--once they are differentiated--is fixed within one individual, the number of these bands varies interindividually.