Figure 11. Müllerian duct (md) development can be subdivided into three phases. First some cells of the coelomic epithelium (ce) are specified to become Müllerian cells and acquire Lim1 (211) and AMHRII (215) expression. Second, they invaginate caudally towards the Wolffian duct (wd). Third, the Müllerian duct elongates caudally towards the urogenital sinus, following the path of the Wolffian duct, whose integrity is required for Müllerian growth. Müllerian cells are shown in blue, proliferating Müllerian duct precursor cells in red, coelomic epithelium in brown and the wolffian duct in yellow. Reprinted from ref. (211) : Orvis & Behringer, Developmental Biology 306: 493–504 (2007) with permission of Elsevier (copyright 2007).