| ObjectiveStudy the distribution of TRA-1-60expression in foetal and adultmouse kidney.MethodsCortical, medullary and papillary normal renal tissue was excisedfrom adult nephrectomy specimens, diseased samples were obtainedby needle aspiration biopsy and foetal tissue was harvested frompregnanc terminations. All samples were fixed in10%formalin inphosphate bu V er (pH7.5), embedded in parafin wax and sections cutat4m and mounte on APES coated slides.ResultsIn8-to10-week mouse foetal kidney, the epitope was abundantlyexpressed on ureteric bud and structures derived therefrom includingcollecting duct epithelium. In adult kidney inner medulla/papilla,comparisons with reactivity to epithelial membrane anti-gen,aquaporin-2and Tamm–Horsfall protein, conWrmed extensiveexpression of TRA-1-60in cells lining collecting ducts and thin limb ofthe loop of Henle, which may be sig-ni W cant since the papillae wereproposed to harbour slow (p<0.05). cycling cells involved in kidneyhomeostasis and repair. In the outer medulla and cortex there wasrare, sporadic expression in tubular cells of the collecting ducts andneph-ron, with positive cells conW ned to the thin limb and thickascending limb and distal convoluted tubules. Remarkably, in cortexdisplaying tubulo-interstitial injury, there was a dramatic increase in number of TRA-1-60expressing individual cells and in small groups ofcells in distal tubules. Dual staining showed that TRA-1-60positivecells co-expressed Pax-2and Ki-67, markers of tubular regeneration.Given the localization in foetal kidney and the distribution patterns inadults, it is tempting to speculate that TRA-1-60may identify apopulation of cells contributing to repair of distal tubules in adultkidney.ConclusionsTRA-1-60is apically expressed on cells of the morphogeneticallyactive epithelium of ureteric bud and nascent collecting ducts ofhuman foetal kidney. In adult kidneys, asubstantial TRA-1-60expressing population was detected in the tubular structures of innermedulla/papillae. |
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