The purpose of this application is to request funds to establish a multi-user facility for video-enhanced and image-intensified light microscopy and image processing. The system requested consists of the following items of equipment: 1) a Zeiss Model ICM 405 inverted photo-microscope equipped for high-resolution phase contrast, differential interference contrast and fluorescence microscopy; 2) three video cameras: a Newvicon camera for video contrast enhancement at normal light levels, a SIT camera for intermediate levels of image intensification, and an ISIT camera for maximum levels of image intensification; 3) a video disc recorder for storing processed video images with minimum distortion and a high resolution video tape recorder for the storage of large volumes of raw data; 4) the Image-I image processor for enhancing, manipulating and quantifying video images; 5) a dot matrix printer for hard copy recording of data from the image processor; and 6) a Leitz micromanipulator for microinjection studies. These items of equipment will comprise a single unit that will be dedicated exclusively to video enhanced light microscopy. The studies that will utilize this equipment include: 1) the role of actin binding proteins in regulating the structure and function of the egg cortical cytoskeleton during fertilization and early embryogenesis; 2) the histotopographical analysis of testis-specific membrane antigens during mammalian spermatogenesis; 3) studies of primate breeding and embryo transfer; 4) interactions between cytoskeletal proteins and the plasma membrane in cultured mammalian cells, and 5) the relationship between the dimensions of the paracellular space and paracellular resistance in intestinal epithelia.