Developmental distribution of PMCA isoforms in the CA1 area of hippocampal Ammon's horn. At P0, all isoforms were weakly expressed. Expression levels increase at P8 for PMCA1 and 2 and at P15 for PMCA3 and 4. At P30 stage, all isoforms showed similar immunoreactions. They were located in the plasma membrane of the soma of developing pyramidal neurons (arrowhead) and in the neuropil (asterisk) of stratum oriens (so) and stratum radiatus (sr). Cytoplasm of cell bodies was PMCA-negative. pcl, pyramidal cell layer. Scale bar: 50 μm.