Hippocampus is located inside the temporal lobe, alongside the amygdala, medial to the inferior horn of the lateral ventricle. The hippocampus is a part of the hippocampal formation and is an inward folded continuation of the cerebral cortex. This brain region includes the entorhinal cortex, subiculum, hippocampus proper (CA1-3 and dentate gyrus).
Important cell types of the hippocampal formation are:
Glutamatergic pyramidal neurons located in the cortical areas and CA regions, granule cells located in the dentate gyrus and interneurons are populating different subfields of this brain structure.
Pyramidal cells in the CA regions are densely packed in a single layer. The dendrites of these cells receiving input from other regions of the hippocampal formation are located on both sides of the pyramidal cell layer. The dentate gyrus granule cells are also packed in a single cell layer. These cells have their dendritic trees located in the molecular layer. The axons of these neurons are called mossy fibers and innervate the CA3 pyramidal neurons. The dentate gyrus is one of the brain regions wherein the fully developed brain still new neurons are formed (neurogenesis).
Hippocampus is an important structure for memory, especially for consolidation of short term memory into long term memory, through a process called long term potentiation (LTP), a strengthening of synaptic pathways through neuronal activity in those pathways. The hippocampus is also involved in spatial memory, which is needed when navigating through your environment.