The histopathology of the kidney in congenital syphilis is still in a state of confusion. Unacquainted with the histology of the new-born and of the fetus, many investigators are continually pointing out as abnormal that which is simply an expression of incomplete development.
The nephrogenic or neogenic zone of the kidney is a continuous layer of developing uriniferous tubules and glomeruli lying beneath the capsule. As each generation of tubules and glomeruli complete their development, the remains of the new-growing tubules are pushed toward the periphery of the kidney. This appositional growth is continued until the nephrogenic zone vanishes, and the development of the kidney is complete, so far as the formation of new elements is concerned. Further growth consists only of the enlargement of the tubules and glomeruli already present.
Authors have never been in agreement as to the exact time or the limits of variability when appositional growth