A whole image of the hippocampal pyramidal neuron revealed by intracellular pressure-injection of horseradish peroxidase.

The intracellular pressure-injection of HRP was applied to the rat hippocampus and has brought an excellent presentation of the Golgi-like image of the pyramidal neuron. Rats were allowed to survive for 3 days and brain sections were treated with the PAP-immunohistochemical technique to enhance the sensitivity of HRP neurohistochemistry. The pyramidal neuron densely developed axon branches in the ipsilateral hippocampus and sent the commissural axon to the contralateral hippocampus. Moreover, short axon branches diverged from the commissural axon to the bilateral septal nuclei.