ULTRASTRUCTURAL FINDINGS IN NEONATAL OBSTRUCTIVE NEPHROPATHY

BOCANEGRA MARIA VICTORIA; RINALDI TOSSI MARTIN; VICENTI AMANDA; GARRAMUÑO VALLES PATRICIA; FORNES MIGUEL

Rosario, Santa Fé , Argentina

Congreso; 10º Congreso Interamericano de Microscopía Electrónica (CIASEM 2009). 1er Congreso de la Sociedad Argentina de Microscopía (SAMIC 2009) Congreso Internacional; 2009

CIASEM 2009). 1er Congreso de la Sociedad Argentina de Microscopía (SAMIC 2009)

ULTRASTRUCTURAL FINDINGS IN NEONATAL OBSTRUCTIVE NEPHROPATHYBocanegra V 1, Vincenti A 2, Rinaldi Tosi M 1, Valles P 1, Fornes M 2.1- IMBECU-CONICET (National Council of Scientific and Technical Research of Argentina)2- IHEM- Facultad de Ciencias Médicas. Universidad Nacional de Cuyo. Mendoza. ArgentinaCongenital obstructive nephropathy, the major cause of chronic renal failure in infancy, is characterized by impaired renal growth and reduction in nephron number. Apoptosis destruction of renal tubular cells resulting from urinary tract obstruction, leads to tubular atrophy, a hallmark of obstructive nephropathy (1). Furthermore, the severity of the apoptotic response to unilateral ureteral obstruction (UUO) is far greater in the neonatal than in the adult rat (2).Among the several stimuli involved, including inflammatory mediators and ischaemic cellular injury, the mechanical signal was shown to be an important inducer of tubular cell apoptosis in obstruction. UUO results in increased hydrostatic pressure of the renal collecting system, which in turn leads to renal tubule dilatation. Mechanical deformation has been considered to be an insult sustained by tubular epithelial cells that directly induces apoptosis. We have previously reported in 14 day obstructed rat kidneys, greater number of apoptotic cells in proximal tubules (PT) and cortical collecting ducts (CCD) by TUNEL technique.To further confirm the presence of apoptotic cells, in this study we examined the early unilateral ureteral obstruction (UUO) effect on PT and CCD epithelial cell morphology.Kidneys from UUO or sham operated rats were isolated after 14 days, then 5mm cubes from cortex sections were studied by classical TEM methodology.In sham operated rats, densely apical microvillus and a great number of mitochondria were found in PT cells (Figure 1b, 1c, 1d). In contrast, in obstructed PT cells, mitochondria number was reduced and microvillus appeared disperse and decreased in number (Figure 3a ). In CCD (Figure 2), we found a relative preserved ultrastructual cells with 2 types of intracellular vacuoles; one of them, small vacuoles with electron- dense material, the second, bigger vacuolas with electron-lucent material. Increased apoptotic cells, with ripple nuclear membrane and dispersed nuclear material were observed in PT and CCD segments in UUO (Figure 2d, 2e).Conclussion: We confirmed the presence of epithelial apoptotic cells in PT and CCD segments in UUO. Intensive damage of epithelial cells from PT at ultrastructural level was also found.Further studies are need to evaluate the progressive development of morphological tubular cell changes leading to tubular atrophy; at varying time intervals following UUO.REFERENCES:1- Gobe GC, Axelsen RA. Genesis of renal tubular atrophy in experimental hydronephrosis in