. "Any process that initiates the formation of a mammary placode through a mechanism that mediates the transfer of information from a mesenchymal cell to an epithelial cell resulting in the epithelial cell adopting the identity of a cell of the mammary placode." . . . . . . "positive regulation of mammary placode formation by mesenchymal-epithelial signaling" . "positive regulation of mammary placode formation by mesenchymal-epithelial signalling" . .