Vascular architecture modifications in the steroid-induced polycystic kidney

This paper presents a study of the renal vascular architecture in polycystic kidneys induced in newborn rabbits by a single injection of methylprednisolone acetate. Ink perfusion and polyester resin corrosion casts were utilized, and the vasculature was studied by light and scanning electron microscopy. Vascular alterations were observed in the two main evolutive stages of the renal polycystosis: the stage of tubular cysts and the stage of glomerular cysts. These alterations were compared with the normal vascular pattern of control kidneys. At the tubular cyst stage the sinusoidal vascular cortical plexus persisted for a long period of time and the superficial cortical glomerular tufts were poorly developed. At the glomerular cyst stage, the vascular architecture of the superficial cortex showed numerous alterations. The glomerular tufts were small and their structural pattern was affected. Frequently the hilum was very wide and the afferent and efferent arterioles were on opposite sides of the glomerular tufts. The afferent arterioles were variable in size and length. Sometimes the glomeruli showed several afferent arterioles. There were numerous cases of double efferent arterioles in the superficial glomeruli of the polycystic kidneys. Various types of aglomerular shunts were observed regardless of the cystic stage or age. These data indicate that, in addition to the cysts, the corticoid-induced polycystic kidneys showed alterations of the renal vascular architecture which are interpreted as a malformation. We suggest, on the basis of these morphologic observations, that the pathogenesis of the polycystic kidneys is not related to the vascular alterations.