Male Tac chromosome identification. (a) Tac 27 is a pair. (b) Paint X1 identifies X1 and Y1q. (c) Paint Y1 covers chromosome Y1 and X1p. (d) Paint X2 identifies X2 and the region of homology on Y1 and Y2. (e) Paint Y2 identifies Y2 and the region of homology on X2 and X3. (f) Paint X3 covers X3 and the pairing region on Y2. (g) Paint Y3 identifies chromosome Y3; no homologous regions were observed. (h) Paint X4 covers X4, Y3 and a heterochromatic centromeric region on Oan 22 or 23. (i) Paint Y4 identifies Y4 and the region of homology on X5. (j) Paint X5 covers X5 plus the pairing region on Y4. The arrow head points to a heterochromatic centromeric region on an autosome.