The present invention relates to the use of fluorescently labeled nucleic acid probes to identify and image analytes in a biological sample. In the preferred embodiments, a probe is provided that comprises a target region able to specifically bind an analyte of interest and an initiator region that is able to initiate polymerization of nucleic acid monomers. After contacting a sample with the probe, labeled monomers are provided that form a tethered polymer. Triggered probes and self-quenching monomers can be used to provide active background suppression.