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 sa c and adrenal glands between embyronic days (ED) 5-20 as well as in ch ick organs after hatching. Sections from snap frozen tissue fixed in c old cacodylate-buffered 2% glutaraldehyde were processed by cerium-DAB -Co-H2O2 methods for benzylamine OX, diamine OX, histamine OX, alpha-h ydroxyacid OX, D-amino acid OX (AAOX) and monoamine OX (MAOX). Prenata lly, only activities of AAOX and MAOX could be demonstrated. AAOX appe ared primarily in the proximal tubular cells of both types of kidneys. In the metanephros the enzyme was also detected in the thick ascendin g limbs of Henle's loops. The amount of reaction product in tubular ce lls increased with their maturation. MAOX activity was detected in imm ature 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 a rterioles 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 epitheli al cells from that in smooth muscle cells. Benzylamine OX, diamine OX and histamine OX were detected postnatally in smooth muscle cells of t he arterial media and muscularis externa of the intestinal wall with l ow 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 o f the vascular wall.