Simone Codelluppi and Lars Borm have developed and optimized a cyclic smFISH protocol, termed ouroboros smFISH, to quantify the expression of a large number of genes in tissue sections. The goal was building a cell type map of the mouse somatosensory cortex. The results are really impressive. See the fantastic images and interactively explore the data using the Loom viewer here.
Great news are not only is taht Lars and Simore have put a lot of effort to make it possible for any lab to set up the method and they provide detailed protocol and a polished software package.