The procerebrum in Helix aspersa extends anteriorly from the cerebral ganglion under the olfactory and peritentacular nerves, which pass over the division between the neuropil and the neuronal cell bodies of the procerebrum. The hollow cerebral tube is connected to the lateral, ventral side of the procerebrum The relations of the olfactory nerve and the neuropil to the neurons in the procerebrum can be seen when the neuropil is stained with antibodies to SCP. Only a small number of neurons near the peripheral surface of the procerebrum are immunoreactive to SCP antibodies, but in the neuropil there are many small immunoreactive processes. It is typical for antibodies to SCP, TPep, and FMRFamide that there is no immunoreactivity at the procerebral apex where neurons are being added Neuron-free cavities in the procerebral apex connect with the cerebral tube (Fig. 2A, B). Dividing cells around these cavities and in the cerebral tube can be seen with either Sytox Green DNA fluorescence or fluorescence from TRITC that is bound to anti-phospho-histone H3 antibodies. The two methods are slightly different in that anti-phospho-histone H3 antibodies do not show mitosis in telophase (Fig. 2C, D). Unlike DNA fluorescence, which is present in all the nuclei, anti-phospho-histone H3 antibodies can show mitosis in a z-projection of a confocal stack of the procerebrum. In the second week post-hatch, a large number of cell divisions are occurring around the cavities in the apex