Persistent foetal lobulation of adult kidney is due to

In humans, embryologically, the kidneys originate as distinct lobules that fuse as they develop and grow. The lobulation of the fetal kidney is usually lost as the lobules become bonded together by the growth of new coex and the renal capsule. Persistent fetal lobulation is a normal variant seen occasionally in adult kidneys . It occurs when there is incomplete fusion of the developing renal lobules.It is often seen on ultrasound, CT or MRI as smooth indentations of the renal outline in between renal pyramids. They should be distinguished from renal coical scarring , which generally overlie the pyramids. Reference : radiopaedia.org/aicles/persistent-fetal-lobulation-of-the-kidneys