In contrast, in sections stained for calretinin, the entorhinal cortex is more lightly stained than the parasubiculum, which has a darkly stained superficial layer, and a densely stained group of neurons in layer III. The border between the entorhinal cortex and perirhinal cortex is also easily distinguished in parvalbumin-stained material while the entorhinal cortex is darkly stained, the perirhinal cortex is lightly stained. Further, both the border with the perirhinal cortex and the border with the parasubiculum are characterized by dark-stained bands of AChE. The 2nd incision is about 1.5-2mm in front of the first one, this incision you need cut into the lateral ventricle, both of the incisions go to the ventral of the brain and meet there. Histochemically, in acetylcholinesterase (AChE)-stained material, MEA is characterized by darker-stained bands in the superficial layer (i.e., layer I) and in the lamina dissecans, in contrast to LEA, which is more evenly stained for AChE. The first incision is at the end of the hemisphere the incision should be about 0.7mm deep for most adult mouse that you might not hurt the hippocampus while to expose it. Further, in LEA there is a relatively cell-free zone between layers II and III this zone is not present in MEA. Cytoarchitectonically, the main difference between LEA and MEA is displayed by layer II neurons: while these are in a dense layer in LEA, they are more dispersed in MEA. Both entorhinal areas are further divided into subfields, i.e., LEA is divided into DLE (dorsolateral entorhinal field), DIE (dorsal intermediate entorhinal field), and VIE (ventral intermediate entorhinal field), whereas MEA is divided into CE (caudal entorhinal field) and ME (medial entorhinal field). The entorhinal cortex is divided into two main areas, i.e., the lateral entorhinal area (LEA) and the medial entorhinal area (MEA). The entorhinal cortex is medially bordered by the parasubiculum, and laterally by the perirhinal cortex rostrally and medially it is bordered by the piriform cortex, whereas caudally and dorsally it is bordered by the postrhinal cortex. The present study describes the cytoarchitectonical and chemoarchitectonical organization of the entorhinal cortex of the mouse (C57BL/6J strain).