Supplementary Fig. 2From: Identification of mediator complex 26 (Crsp7) gametologs on platypus X1 and Y5 sex chromosomes: a candidate testis-determining gene in monotremes?Evolution of the sex chromosome chain from a ring. This alternative model is discussed in Gruetzner et al. (2006) in detail. The homology between X1 and Y5 reported here is the first evidence that a ring structure may have existed in monotremes (JPEG 30 kb)Back to article page