Immunohistochemical study of .GAMMA.-glutamyl transpeptidase during the development and maturation of rat kidney.

Abstract

Gamma-glutamyl transpeptidase (γ-GTP) was localized in prenatal and neonatal rat kidneys using an immunohistochemical method with monoclonal antibodies to rat kidney γ-GTP. γ-GTP was demonstrated on the brush border and basolateral membrane of proximal convoluted tubules from the 18th fetal day. The basolateral membrane of proximal tubules revealed strong reaction at 1 and 3 days after birth. The reaction of basolateral membrane decreased with the maturation of nephrons, however, moderate reaction was still observed at 30 days of age in the S3 segment. Throughout the postnatal development of the kidney, the S3 exhibited the strongest immunostainingand S1 showed the weakest reaction, and proximal tubules in the deep layer of the cortex always provided a stronger reaction than those in the superficial layer of the cortex. Maturating cuboidal and squamous epithelial cells of descending Henle's loop showed a positive reaction on the luminal and lateral cell membranes. On immunoelectron microscopy, γ-GTP was found on the brush border, basolateral membrane, membranes of pinocytotic vesicles and apical invaginations in proximal tubular cells at 1-7 days after birth. However, tight junctions were devoid of the reaction. The development of basal infolding and localization of γ-GTP there seemed to relate closely to the development of surrounding capillaries. γ-GTP was localized on the cell membrane and occasionally in the cytoplasm of interstitial cells of renal interstitium.