Identification of spindle-shaped von Economo-like neurons in the rodent Rattus norvegicus

The absence of spindle cells, or von Economo neurons (VENs), in the cortex of rodents, particularly Rattus norvegicus , has been previously reported. In this paper, we show microanatomic and immunohistochemical evidence of the existence of VENs-like cells in the anterior cingulate cortex (ACC) and in the frontoinsular cortex (FI) of R. norvegicus . For this purpose, NADPH-d histochemistry, immunohistochemistry for nNOS, eNOS, NeuN, GABRQ, dopamine D3R and Nissl staining were performed. The results showed fusiform neurons positive for the aforementioned markers in layers III and V of the ACC and in layers III and V of the FI cortex. Fork neurons were also observed in the same areas. The NADPH-d-positive elements also indicated a close anatomical relationship between some VENs-like cells and blood capillaries. These findings demonstrate the anatomical existence of VENs-like cells in the rat.