RNAscope hybridization demonstrates the expression of CB2R mRNAs in a subset of hippocampal cells. A–C. RNAscope hybridization was performed with a probe that targets the deleted sequence in CB2R KO mice. Hippocampal slices were made from CB2R WT mice. Images were taken from the CA1 (A), CA3 (B) and dentate gyrus (C) regions. Right column, magnified views of the arrow heads shown in the merged images. D–E. RNAscope hybridization in hippocampal sections made from CB2R KO mice. Images from the CA1 region (D) and dentate gyrus (E) show no signal of CB2R mRNAs. The areas indicated by arrow heads are magnified in the right column. pyr, stratum pyramidale; rad, stratum radiatum; mol, stratum moleculare; gra, stratum granulosum; hil, hilus.