Fig. (1).

In situ hybridization of cloned, chromosome-specific PCR products. A) Biotinylated DNA prepared from PCR products with chromosome Y -specific oligonucleotide primers bind specifically to the heterochromatic region of the human Y chromosome. B) The Y-specific probe shown in A) can be combined with a biotinylated probe for the smaller tandemly repeated DNA cluster at the centromeric region of the X-chromosome. Bound probes were detected with avidin-FITC (green fluorescence) on ethidium bromide (red fluorescence) stained chromosomes, here shown as grey scale images. (Bars = 10 µm).