Development of renin expression in the mouse kidney

During metanephric kidney development, renin is expressed in the walls of larger intrarenal arteries, but is restricted to the terminal part of the preglomerular arterioles in the adult kidney. Our study describes the three-dimensional development of renin expression in mouse kidneys during fetal and postnatal life. Renin immunoreactivity first appeared at day 14 of development in the cells expressing α-smooth muscle actin (αSMA) in the arcuate arteries. Before adulthood, the branching of the arcuate arterial tree increased exponentially and renin expression shifted from proximal to distal parts of the tree. Renin expression at branching points or in the cones of growing vessels was not seen. Instead, renin expression appeared after vessel walls and branches were already established, disappeared a few days later, and remained only in the juxtaglomerular regions of afferent arterioles. In these arterioles, coexpression of renin and αSMA disappeared gradually, with the terminal cells expressing only renin. At all stages of kidney development, renin expression among comparable vessel segments was heterogeneous. Renin expression remained stable after it reached the terminal parts of afferent arterioles.