Fig. 1. The regressing Müllerian duct expresses MMP2. (A) Gelatin zymography was carried out on E13 mouse genital ridge extracts and the corresponding MMP activity is shown in the second lane (E13 GR). Lane 1 shows zymography of purified recombinant MMP2 (1 ng), as a control marker. Zymography reveals both the inactive proenzyme and mature metalloproteinase; most of the activity detected in cell extracts of genital ridges represents the intracellular pro-form of MMP2. This zymogram is shown as a negative image. (B) Whole-mount in situ hybridization of MMP2 profiles showed prominent expression in male but not in female E13 Müllerian ducts (M, arrow). Control experiments using an MMP2 sense probe showed no signal in the Müllerian duct (data not shown). The prominent signal observed in the ovary and testis was observed with both sense and antisense MMP2 probes. O, ovary; T, testis. (C) In situ hybridization of MMP2 in E13 genital ridge sections shows marked expression in the Müllerian mesenchyme, which encapsulates the visible epithelial Müllerian duct (M) in male tissue. The MMP2 staining observed in the coelomic epithelium (CE) in female tissue is indicated with an arrowhead.
