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Perinatal development of the rat kidney: proliferative activity and epidermal growth factor
T Okada1, A Iwamoto, K Kusakabe
1Department of Laboratory Animal Science, Division of Veterinary Science, Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, Sakai, Japan.
Insights
Kidney cell proliferation, marked by proliferating cell nuclear antigen (PCNA), decreases during perinatal development. Epidermal growth factor (EGF) is crucial for kidney cell proliferation and maturation.
Area of Science:
- Nephrology
- Developmental Biology
- Cell Biology
Background:
- Kidney development involves complex cellular proliferation and differentiation processes.
- Understanding perinatal kidney development is crucial for identifying potential causes of congenital kidney diseases.
Purpose of the Study:
- To investigate the spatiotemporal patterns of cell proliferation in the perinatal rat kidney.
- To examine the role of epidermal growth factor (EGF) and its receptor (EGFR) in kidney development.
Main Methods:
- Immunohistochemistry was used to localize proliferating cell nuclear antigen (PCNA), EGF, and EGFR in perinatal rat kidneys.
- PCNA-positive cell ratios were quantified in glomeruli and tubules as an index of proliferative activity.
Main Results:
- PCNA-positive cell ratios significantly decreased in glomeruli and proximal tubules during the perinatal period.
- PCNA-positive cells were concentrated in the nephrogenic zone, particularly in collecting ducts and straight proximal tubules.
- EGF was detected in tubules and collecting ducts, with decreased expression in proximal tubules postnatally.
- EGFR was present in proximal tubules, collecting ducts, and immature glomeruli.
Conclusions:
- Kidney cell proliferation diminishes with age during the perinatal period.
- EGF signaling is vital for glomerular cell proliferation and for the proliferation and maturation of proximal tubule and collecting duct cells.
Abstract:
The immunolocalization of proliferating cell nuclear antigen (PCNA), epidermal growth factor (EGF) and its receptor (EGFR) was examined in the perinatal rat kidney. As the index of proliferative activity, PCNA-positive cell ratios in glomeruli and proximal tubules were determined. The PCNA-positive ratios in both glomeruli and proximal tubules decreased significantly during the perinatal period and tended to decrease as the glomerular developmental stage proceeded as well. PCNA-positive cells were seen predominantly in the nephrogenic zone of the kidney throughout the period examined. They were noted in the collecting ducts of the nephrogenic zone and were rarely seen in those of the central zone of the kidney. On the other hand, PCNA-positive cells were noted in the straight portion of the proximal tubules and were rarely seen in the convoluted one. EGF-positive cells were seen in the proximal tubules, distal tubules and collecting ducts, though EGF-positive cells in the proximal tubules decreased after birth. EGFR-positive cells were seen along the entire length of the proximal tubules and collecting ducts as well as in immature glomeruli, not in mature ones. These results indicate that marked cell proliferation occurs in the collecting ducts in the peripheral area and in the proximal tubules in the central area of the kidney, that the proliferative activity decreases with age during the perinatal days and that EGF plays an important role in the proliferation of glomerular cells, and in both proliferation and maturation of the cells in the proximal tubules and collecting ducts.