Tac chromosome paints hybridized to male Oan metaphases. (a) Paint Tac X1 (red) hybridized to Oan X1 and Oan Y1q. Paint Tac X2 (green) hybridized to Oan X2 and the pairing region on Oan Y2 and Y1p (arrow head). (b) Paint Tac Y2 covers Oan Y2 and hybridized to Oan X2 and Oan X3. (c) Paint Tac X3 hybridized to Oan X3 and the pairing region on Oan Y2, the two additional signals are centromeric heterochromatin. (d) Tac paint X5 hybridized to Oan 12p. (e) Paint Tac Y4 (red) hybridizes to Oan 12p, and to Oan X5p and Oan Y4p. Paint Tac 27 identified Oan Y3, Oan X4, and Oan Y4q. (f) Paint Tac X4 covers Oan X5.