Ume Eder Bat (A beautiful child) (popular song from Basque folklore) The aim of this monograph is to introduce the postnatal development of morphological features that are relevant to readers interested in the neurobiology and pathology of the hippocampal formation in terms of the complex phenomena that underlie the progressive anatomical and functional maturation of this brain region. This review focuses on the morphological aspects, while more detailed basic phenomena associated with neuronal maturation--which are undoubtedly also of great interest--are only marginally referred to, although...