MACULA DENSA CELLS OF MOUSE KIDNEY DO NOT SYNTHESIZE EPIDERMAL GROWTH-FACTOR PRECURSOR MESSENGER-RNA

Epidermal growth factor (EGF) has previously been found in cells of the thick ascending limb of Henle's loop (TALH) and the first part of the distal convoluted tubule (DCT) of mouse kidney. To define the cellular localization of the mRNA that encodes the protein precursor of EGF, we used high-resolution in situ hybridization. EGF precursor cDNA was hybridized to both paraffin-embedded and frozen sections of mouse kidney. EGF precursor mRNA was detected in cells comprising the TALH and the first part of the DCT. In contrast, tubular cells in the macula densa did not express this specific mRNA. The results indicate that expression of the EGF precursor gene is restricted to specific types of cells in the distal nephron.