Representative photomicrographies of normal jejunum showing the region of villi (A) and crypt (B); jejunum of MTX treated rat showing blunted villous recovered with flattened and vacuolated cells, and presenting inflammatory cell infiltration on the lamina propria (C) and crypt necrosis with neutrophil infiltration (D); systemic administration of aminoguanidine (E and F) and L-NAME (G and H) reduced the villus height atrophy as well as crypt destruction in the segments of jejunum. Hematoxylin and eosin staining. Magnification 400x. Scale bar lengths 10 μm. The arrow indicates neutrophils within a necrotic crypt.