Figure 7.

Double immunolabelling for calbindin and calretinin using DAB and DAB–Ni as chromogens. The control CA1 immunostaining for calbindin (DAB, brown reaction product) labels interneurons in all layers and pyramidal cells. Calbindin-positive interneurons and pyramidal cells are clearly distinguishable on the basis of the intensity of staining, their morphology and location. Immunostaining for calretinin (DAB–Ni, black reaction product) labels numerous interneurons in the CA1 region. The dendrites of calbindin-positive interneurons often receive multiple contacts from calretinin-positive axon terminals both in control (A, arrows) and non-sclerotic epileptic (B, arrows) samples. These are presumably inhibitory contacts originating from local calretinin-positive interneurons. The examined calbindin-positive dendritic segments are located in the stratum oriens or radiatum close to the stratum pyramidale, these layers are devoid of calretinin-positive terminals giving asymmetric synapses. Scale: 10 µm.