Objective: Multicystic renal dysplasia (MRD) causes perinatal mortality and infantile renal failure. Dysplastic kidneys contain dilated tubules surrounded by immature mesenchyme, cartilage, muscle and nerve. Several growth and transcription factors are implicated in renal development in animal models, but there are very few human studies so far.

Method: We selected 20 autopsies with MRD, 17 controls and 19 fetal–embryonic kidneys (gestations between 3.5 and 19 weeks). Immunohistochemical staining with Pax2, transforming growth factor beta (TGFβ), BLC2, and β-catenin were localised and quantified.

Results: Pax2 stained the nuclei of dysplastic tubular epithelium and subcapsular non-dysplastic tubules, the nephrogenic zone and proximal tubules of controls and was strongly positive in the nephrogenic zone and some tubules in fetal kidneys. The intensity of staining decreased with age. Pax2 was not detected in mature glomeruli. TGFβ staining was negative in MRD, controls and fetuses–embryos. BCL2 stained the cytoplasm of dysplastic tubules. In controls, it was positive in the nephrogenic zone, proximal tubules and medulla. In fetal kidney, the subcapsular staining formed a cap around S-shaped bodies. β-Catenin exhibited membranous staining in dysplastic tubules and some subcapsular non-dysplastic tubules. It was seen in the nephrogenic zone and medulla of controls and in fetal tubules and glomeruli.

Conclusions: Pax2, BCL2 and β-catenin are expressed in dysplastic tubular epithelium and even stronger in the nephrogenic zone of fetal and infantile kidneys; renal mesenchyme is negative in normal and dysplastic kidneys. In controls, the intensity of Pax2 staining decreases as the kidney matures. TGFβ is not expressed in MRD, controls or fetal–embryonal kidneys.