Abstract: A series of devices for in vivo imaging of cellular architecture in a variety of tissues. A 200 MHz transducer is mounted on the tip of a cardiac catheter, gastroscope, colonoscope, bronchoscope, laparoscope or similar device, where it is moved mechanically to produce B-mode images of cells in the tissue. The ultrasound beam is focused in a subsurface region of tissue, and ultrasound which is backscattered from the focal zone is analyzed to produce images. Because heart motion may interfere with cardiac imaging, images are gated in mid-diastole for cardiac applications.