Perinatal development of the rat kidney: Proliferative activity and epidermal growth factor

The immunolocalization of proliferating cell nuclear antigen (PCNA), epider mal growth factor (EGF) and its receptor (EGFR) was examined in the perinat al rat kidney. As the index of proliferative activity, PCNA-positive cell r atios in glomeruli and proximal tubules were determined. The PCNA-positive ratios in both glomeruli and proximal tubules decreased significantly durin g the perinatal period and tended to decrease as the glomerular development al stage proceeded as well. PCNA-positive cells were seen predominantly in the nephrogenic zone of the kidney throughout the period examined. They wer e noted in the collecting ducts of the nephrogenic zone and were rarely see n in those of the central zone of the kidney. On the other hand, PCNA-posit ive cells were noted in the straight portion of the proximal tubules and we re rarely seen in the convoluted one. EGF-positive cells were seen in the p roximal tubules, distal tubules and collecting ducts, though EGF-positive c ells in the proximal tubules decreased after birth. EGFR-positive cells wer e seen along the entire length of the proximal tubules and collecting ducts as well as in immature glomeruli, not in mature ones. These results indica te that marked cell proliferation occurs in the collecting ducts in the per ipheral area and in the proximal tubules in the central area of the kidney, that the proliferative activity decreases with age during the perinatal da ys and that EGF plays an important role in the proliferation of glomerular cells, and in both proliferation and maturation of the cells in the proxima l tubules and collecting ducts. Copyright (C) 2001 S. Karger AG. Basel.