Lectins WGA and LASA as selective histochemical markers of rat kidney

Abstract

Selective detection of individual types and subpopulations of cells, extracellular structures of organs and tissues continues to be a relevant area of modern morphological science. Aim. To investigate the applicability of wheat germ agglutinin (WGA, specific to DGlcNAc, NeuNAc) and Laburnum anagyroides seeds agglutinin (LASA, specific to LFuc, DGal) for selective histochemical labeling of renal constituents of adult and newborn rats. Results and Discussion. In the kidneys of adult rats WGA label was restricted to filtration membrane, podocytes and mesangial cells of renal corpuscles, brush border of proximal tubules, cytoplasmic glycoconjugates in the apical part of the distal tubule cells, as well as to plasma membranes of the luminal surface of collecting ducts. In the kidneys of newborn rats WGA receptor sites were selectively exposed on the luminal surfaces of sub-capsular S-shaped bodies and of developing nephrons tubular network. With respect to LASA, structural components of renal parenchyma of the adult rats demonstrated moderate homogeneous reactivity accompanied with enhanced LASA affinity to podocytes and mesangial cells nuclei, this mode of labeling being significantly different from WGA receptor sites histotopography. In the neonatal rat kidneys there was detected an intense selective binding of LASA to cytoplasmic glycoconjugates of the developing midrenal tubular network, subcapsular and medullary parts of renal parenchyma being completely non-reactive. According to the obtained data, WGA can be recommended for selective histochemical labeling of renal corpuscles filtration membrane, podocytes and mesangial cells, as well as for brush border of proximal tubules and luminal plasma membrane of collecting ducts of adult rat kidneys. LASA lectin selectively marked developing midrenal tubules of neonatal rats, this option may be of certain significance in embryological studies. Conclusions. Due to the high content and vast diversity of glycoconjugates, rat kidneys can be recommended as an adequate model for testing lectin histochemistry protocols, in particular, while studying histochemical specificity of new lectin preparations. The organ morphogenesis is accompanied by significant remodeling of carbohydrate determinants, which can influence selectivity of organ structures labeling. Additional staining of the cell nuclei by hematoxylin after lectin receptor sites visualization can be considered an alternative method that allows more precise identification of carbohydrate histotopography, as well as for morphometric studies. However, it should be kept in mind that both dyes can be overlapping, creating certain difficulties in the interpretations of results.

Keywords

• rat kidney, selective labeling, postnatal morphogenesis, lectin histochemistry