Characterization of the Porcine Cingulate Sulcus Cytoarchitecture.

Cortical folding (gyrification) is a unique process by which the brain can expand and increase surface area while confined by the boundaries of the inner wall of the skull. Although there is still much debate about the exact mechanisms concerning the genetic and cellular factors involved in this process, gyrification results in a heterogenous organization of neuronal layering and cell types not seen in the smooth, lissencephalic brain of rodents. In this article, we describe differences in neuronal density and supporting cells within the depths (fundus) and adjacent walls of the cingulate sulcus of the porcine brain. We also measured the distance between pyramidal neurons within Layers III and V to investigate if the observed increase in density of neurons within the cingulate fundus is associated with a decrease in distance between neurons in these layers. We also identify the presence of the gigantopyramidal neuron within the fundus of the porcine cingulate sulcus, a pyramidal neuron subtype seen in nonhuman primates and human brains. Taken together, this article provides evidence that further supports the heterogeneous composition of the gyrified brain by describing the cellular organization of the porcine cingulate sulcus.