A microfluidic flow cell subassembly, which may be assembled into a flow cell having fluidic connections outside of the main substrate, is described for encapsulating a sample to allow for subsequent controlled delivery of reagents to the sample, such as multiplexed in situ biomarker staining and analysis. The fluidic connectors are thin film fluidic connectors capable of connecting to a fluid delivery system. The subassembly may be sealed against a solid support to form a flow cell. Methods of use are also disclosed.