From:

C. R. Medical Scientific Foundation (FUMCER)*  and
National University of  Río Cuarto**

ABSTRACT
Nowadays it is a controversial matter to elucidate if a sterile reflux provokes renal injury and produces tubulo-interstitial nephropathy. During a decade ( 1986/96) the Río Cuarto Team studied and selected 30 pigs in experimental model. The main objective was to demonstrate our hypothesis: that an vesico-ureteral (extravesical) reflux, without infection (sterile) and changes in the bladder outlet, provoked reflux nephropathy (1, 2 ).
We found important changes in the kidney parenchyma  that demonstrated a peculiar focal and segmentary tubulo-interstitial nephritis similar to the reflux nephropathy.
Histopathology: Macroscopically and in an early stage a "horse-shoe" ureteral meatus, and flexuose, enlarged left ureter and edema in parenchyma were observed.

Microscopically:
At 30  days we observed: mononuclear cellular infiltration; .hiperchromatic nucleus; disruption tubular basal membrane; eosinophilic materia at tubular lumen; flattening Bowman capsule; early fibrogenesis.
Between 120/150 days appeared hialinotic and hidropic degeneration; atrophic and flattened tubular cells; periglomerular fibrosis; epithelial atrophy;  apparent loss of tubules and glomeruly and renal scars.

We concluded that vascular, chemical, humoral, urodynamic and immunological process can also generate reflux nephropathies.