Photoacoustic imaging is an advanced biomedical imaging technique that combines optical excitation and ultrasound detection to provide molecular functional information of biological tissues in vivo. From the underlying principles, the spatial resolution and imaging depth of the photoacoustic imaging system can be adjusted. In recent years, photoacoustic imaging has gained increasing attention for its potential in high-resolution microscopy, particularly in the context of cellular visualization. A wide range of techniques, including laser scanning, wavelength tuning, transducer design, and data acquisition strategy, have been explored to enhance resolution in photoacoustic imaging. These advances have enabled detailed imaging of cell nuclei, organelles, chromophores, and molecular distributions. This review highlights recent advancements in high-resolution photoacoustic imaging techniques aimed at visualizing cellular structures. We explore key system configurations, imaging methodologies, and representative biomedical applications, including label-free histopathological imaging, biochemical mapping, deep-tissue microscopy, and super-resolution imaging techniques. By summarizing these achievements, we aim to highlight the current state and future potential of photoacoustic imaging as a critical tool in cellular and molecular biomedical research.
