Origin of apoptotic cells in the interstitium of the superficial cortex of newborn mouse kidneys *
To clarify the origin and localization of apoplolic cells in the superficial renal cortex of newborn mice, kidneys from two-day-old neonates were examined by light and electron microscopy. The cortex of the newborn mouse kidney contained ureteric buds, numerous metanephric tissues at various stages of nephron development, such as metanephric tissue caps, comma-shaped and S-shaped metanephric vesicles, and abundant cortical interstitium. The inlerstitium consisted of dendritic interstitial cells, which formed a supportive network around the metanephric tissues, and newly formed capillaries. Dying cells stained by the TUNEL assay were noted in the superficial cortical interstitium. TUNEL-positivc cells showing chromatin compaction and margination were often localized in the cortical interstitium near the medullary edge of the metanephric tissue caps. A few metancphroblasts showing chromatin condensation also appeared within the metanephric tissue caps, and some of the interstitial dcndritic cells extended their cytoplasmic processes into the metanephric tissue caps and contained large phagolysosomes. Since the interstitial cells near the medullary edge of the metanephric tissue caps often contained numerous apoptotic bodies, the majority of apoptotic cells in the interstitium of the superficial renal cortex of neonatal mice could be considered to originate from metancphroblasts in the metanephric tissue cap beneath the renal capsule. (Acceptcd on July 19, 1999) Kawasaki Igakkaishi 25(3 ) : 157-163, 1999
