Large-scale normal cell death in the developing rat kidney and its reduction by epidermal growth factor

Area of Science:

• Developmental Biology
• Cell Biology
• Renal Physiology

Background:

• Normal cell death (apoptosis) is recognized in developing vertebrate organs but its role in mammalian kidney development was considered minor.
• Previous research has not emphasized the significance of apoptosis in kidney organogenesis.

Purpose of the Study:

• To investigate the presence and significance of normal cell death in mammalian kidney development.
• To determine the timing, mechanisms, and potential regulators of cell death in the developing kidney.

Main Methods:

• Histological examination of developing rat kidneys to identify cells with apoptotic morphology.
• Time-course analysis of cell death in specific kidney regions (nephrogenic zone, medullary papilla).
• In vivo experiments using epidermal growth factor (EGF) to assess its effect on cell death.

Main Results:

• Normal cell death occurs in both the nephrogenic region and medullary papilla of the developing rat kidney with distinct temporal patterns.
• Approximately 3% of cells in these regions exhibit apoptotic morphology and are cleared rapidly via phagocytosis.
• Epidermal growth factor treatment inhibited cell death, suggesting a role for survival factors.

Conclusions:

• Normal cell death is a substantial and underestimated component of mammalian kidney development.
• The observed cell death may be regulated by the availability of survival factors, such as EGF.
• These findings necessitate a re-evaluation of the role of apoptosis in kidney organogenesis.