Figure 1.

Schematic diagram of common ST techniques. There are two main categories of ST techniques: imaging and sequencing-based. Sequencing-based ST techniques are further classified into LCM-based or 10X Visium spatial sequencing methods. LCM-based spatial sequencing employs LCM dissection to capture the microsection of interest to be further in vitro sequenced. The 10X Visium method utilizes a spatially barcoded sequencing platform. The tissue sample is placed onto the platform without dissection and then in situ sequenced. Imaging-based ST techniques include fluorescent in situ hybridization- and in situ barcoded amplification-based methods. Fluorescent in situ hybridization-based ST techniques rely on direct imaging of individual RNA molecules in single cells using multiple fluorophore-labeled probes. In situ barcoded amplification-based methods are also based on in situ hybridization, but they use a distinct probe called padlock to amplify the hybridization signal through rolling amplification, thereby enhancing transcript capture depth.