Abstract: The present invention relates to an ultrasound visualization system which has a capability of microscopic examination of tissue within the body without the need for removal of the tissue. A transducer, capable of producing and receiving high frequency acoustical beams is positioned within a needle. The acoustical beams are directed radially from the needle and are focused on a point which is outside of the needle and in the tissue. The microscope can be operated in either the pulse echo or pulse reflection mode. The needle can be inserted into a patient, and the acoustical beams are scanned to produce highly magnified images of cellular features of internal tissue or features of tissue architecture and structure helpful to the determination of tissue pathology.