For the first time in the field of medical imaging, harmonious use of Z-contrast imaging and digital image processing was developed as an analytical imaging tool and demonstrated in studying human and rabbit spermatozoa. The biological information generated is unique to the science of medical imaging. The versatility of its applications is wide as this advance in imaging technology can be applied to any area of medicine involving tissue analysis. Tissue analysis plays a vital role in both medical research and diagnostic patient care. Imaging in the Z-contrast mode of the scanning-transmission electron microscope affords biologists the capability to image tissue in its natural state such that heavy metal fixatives and stains are not used. The digitally processed Z-contrast image is not only devoid of artifacts caused by fluctuating mass-density, topography variations, and the addition of heavy metal contrast agents but also offers a biological blueprint of the atomic weight distribution in the tissue. The varying gray level intensities assigned to each pixel in the resulting image are specific to the average atomic weight differences inherent in the tissue. The advent of complementary Z-contrast imaging and digital image processing and their concomitant research possibilities offers areas of medical care and medical research an invaluable imaging tool.