Figure 1.

The locations of break apart probes in the germline IGH locus on chromosome 14. Open boxes indicate constant regions, and black ovals indicate IGH enhancer regions. Constant region/3′probes are shown in red and variable region/5′ probes are shown in green. Dashed lines represent areas of cross-hybridization. The approximate position of the Ig10 cosmid, a 3′ probe used in many other studies, but not in this study, is based on its initial description (Flanagan and Rabbits, 1982).