Colocalization of argininosuccinate lyase (ASL; A and B), carbamoyl phosphate synthase 1 (CPS1; C and D), ornithine aminotransferase (OAT; E and F), and ornithine carbamoyltransferase (OTC; G and H) with argininosuccinate synthase (ASS1) in the small intestine of neonatal (7-day-old; A, C, E, and G) and young (35-day-old; B, D, F, and H) pigs. The different enzymes (in red) are costained with ASS1 in green and DAPI in blue. Colocalization of ASS1 with the different enzymes, if present, appears in yellow. Scale bar, 100 μm. Circles denote the crypt-villus base and rectangles the apical portion of the villus.