Distribution of the sst2A receptor immunoreactivity in the rat hippocampus during pre- and postnatal development.

<p>A–A″) At E16, sst2A receptor immunoreactivity (red in A, A″) is localized in the intermediate zone (IZ) of the hippocampus. Note the lack of immunoreactivity in the ventricular zone (VZ). B–B″) At E21, the most intense immunolabeling is found in the intermediate zone of CA1. In addition, less intense immunolabeling is apparent in the pyramidal cell layer as well as in the strata oriens and radiatum of CA1, in the CA3 and in the developing dentate gyrus (DG). C) In the hilus of the DG, sst2A receptor immunoreactivity appears diffusely distributed. D represents magnification of the area labeled with asterisk in B and illustrates the diffuse sst2A receptor immunolabeling observed in the CA1 pyramidal cell layer. E represents magnification of boxed area in B. The sst2A receptor immunolabeling is intense in cells of the IZ whereas the subventricular zone (SVZ) is devoid of labeling. F) At P3, intense immunofluorescence is detected in the pyramidal layer, strata oriens and radiatum of CA1-3, as well as in the hilus of DG. The molecular layer of dentate gyrus is weakly immunoreactive. G represents magnification of boxed area in F and illustrates the intense sst2A receptor immunolabeling localized in CA1 pyramidal cell bodies and proximal dendrites. H represents magnification of area labeled with asterisk in F and illustrates the diffuse sst2A receptor immunolabeling observed in the hilus of the DG. Scale bars: A–A″, B–B″, F, 100 µm; C, D, E, G, H, 20 µm.