[Do the island neurons of regio entorhinalis belong to the class of pyramid or star-shaped cells?].

Abstract

In the vicinity of the collateral sulcus the cellular islands of the entorhinal region (lamina alpha of the outer principal layer = Pre-alpha) fuse, forming a cellular plate which runs obliquely through the outer laminae. Finally, the cellular elements of Pre-alpha lie in between the third and the fourth layer of the isocortex. The islands are mainly composed of star-shaped nerve cells with thorny dendrites and an axon extending into the white matter. Within the reaches of the oblique plate the shape of these cellular elements underlies an alteration. Apical and basal dendrites become more and more recognizable, the cell body gains the shape of a pyramid. For this reason, we consider the star-shaped neurons of the islands to be modified pyramidal cells. They are compared with the genuine star cells (Golgi-II-cells) of the layer. Distinguishing characteristics not only of the Golgi- but also of the pigment-picture allow the unequivocal distinction between the modified pyramids and the Golgi-II-cells.