. "Any process that modulates the rate, frequency, or extent of mammary gland cord elongation as a result of a signal being created by a mesenchymal cell that is a precursor to the mammary fat and its subsequent reception and interpretation by an mammary cord epithelial cell." . . "regulation of mammary gland cord elongation by mammary fat precursor cell-epithelial cell signaling" . "regulation of mammary gland cord elongation by mammary fat precursor cell-epithelial cell signalling" . .