Fig. 1. Analysis of tissue specific deletion of Sox9 in Sf1:Cre; Sox9^flox/Sox9^flox animals. Transgenic lines carrying the Cre recombinase under a 674 bp Sf1 promoter fragment were crossed onto the homozygous Sox9^flox/Sox9^flox background. (A) The floxed and deleted Sox9 locus. Orange arrows indicate the position of primers used for the detection of the Sox9^flox and the Sox9 allele. (B) Detection of Sox9 deletion in urogenital ridges (E13.5) on the genomic level. Only mice carrying the Sf1:Cre transgene (lanes 3 and 4) show the deleted band Sox9. Incomplete deletion of the floxed allele may be due to inefficient expression of Sf1:Cre or may reflect the contamination of cells from the mesonephros. (C-E) In situ hybridization analysis for Sox9 at E13.5. Dotted lines indicate the outline of the developing gonads. Embryos homozygous for the Sox9^flox allele and carrying the Sf1:Cre transgene (Cre) show reduced (D) or absent (E) expression of Sox9 in the developing gonad. Note the persistent signal of Sox9 in other tissues (e.g. arrow in panel E indicates expression in the neural tube).