Development of hydrogen peroxide (H2O2)-generating oxidases in chick organs with special reference to kidneys.

The developmental pattern of H2O2-producing oxidases (OX) was studied in chick kidneys (mesonephros, metanephros), intestine, liver, yolk sac and adrenal glands between embryonic days (ED) 5-20 as well as in chick organs after hatching. Sections from snap frozen tissue fixed in cold cacodylate-buffered 2% glutaraldehyde were processed by cerium-DAB-Co-H2O2 methods for benzylamine OX, diamine OX, histamine OX, alpha-hydroxyacid OX, D-amino acid OX (AAOX) and monoamine OX (MAOX). Prenatally, only activities of AAOX and MAOX could be demonstrated. AAOX appeared primarily in the proximal tubular cells of both types of kidneys. In the metanephros the enzyme was also detected in the thick ascending limbs of Henle's loops. The amount of reaction product in tubular cells increased with their maturation. MAOX activity was detected in immature enterocytes, in smooth muscle cells of large systemic arteries (on ED 5-6) as well as in proximal tubular cells of the mesonephros and adrenal gland. Later the enzyme appeared also in smooth muscle cells of the intestinal wall and in endothelial and smooth muscle cells of arterioles of the mesonephros. In the metanephros MAOX was detected at the same locations with a time delay because of a developmental shift of the kidney. Inhibition tests revealed that MAOX differs in epithelial cells from that in smooth muscle cells. Benzylamine OX, diamine OX and histamine OX were detected postnatally in smooth muscle cells of the arterial media and muscularis externa of the intestinal wall with low activities. It is concluded that MAOX and AAOX activities represent useful markers in the development of renal tubules. In addition, MAOX activity can be considered an indicator of maturation of components of the vascular wall.