Figure 2 A photomicrograph of hippocampal area sections. (a) Normal structure of the area. (b) Rats treated with toluene show decrease in thickness of this area. Many cells show darkly stained cytoplasm with small nuclei, although the nucleolus is still observed (the upper left corner of the figure). (c) Rats treated with toluene and 150 mg citicoline, where disorganization of neurons is noticed, and damaged neurons are decreased. (d) Rats treated with toluene and 300 mg citicoline show neurons that are close to normal (hematoxylin and eosin, ×200).