Histochemical demonstration of heavy metals in the reptilian archicortex

The topographic distribution of heavy metals has been studied in the reptilian brain by means of Timm's sulphide silver method. Timm-positive histochemical reaction was detected in the archicortex and in the septum. In the first region, the staining pattern yielded evidence of cortical layering and the distribution of mossy fiber terminals. In the septum, uneven distribution of histochemical staining permitted identification of different functional territories. These data show that the reptilian archicortex is in many ways homologous to the mammalian hippocampus and fascia dentata, and also indicate that it undergoes significant remodeling during evolution.