Three male-specific PCR products of the sequences BC1.2, λ ES6.0, and BRY.l were used as probes for Southern blot analyses. Each of these probes generated a complex male-specific band pattern, which showed some quantitative variations among bulls. Hybridization patterns obtained with the BC1.2 and λ ES6.0 PCR products were interrelated. Chromosomal locations of these repeats were determined by hybridizing the tritiated PCR products in situ to male metaphase spreads. The BC1.2 and λ ES6.0 PCR products hybridized to Yp13→p12, whereas the BRY.l PCR product hybridized over the entire Y chromosome. In addition, the BC1.2 and λ ES6.0 PCR products hybridized to the distal half of the acrocentric Y chromosome of Bos indicus, indicating that the short arm of the B. taurus Y chromosome is homologous with the telomeric end of the B. indicus Y and supporting the notion that the Y chromosomes of these two species differ by a pericentric inve