This study on the zebrafish optic tectum is a series of four images with magnifications ranging from the SEM block face overview to of the zebrafish head to high magnification (80,000X) showing optic tectum synapse. The first image is a bloc face SEM image at 200x of the epon embedded zebrafish head. The second image is another block face SEM low magnification image of the tectum. This image, the third image in the series, is a 60,000X TEM image of a OTO fixation and copper lead en bloc staining of zebrafish optic tectum synapse. The fourth image is a 80,000X TEM image of a zebrafish optic tectum synapse. Larval Zebrafish 10 dpf Optic tectum Synapses Osmid (osmium imidazole) OTO fixation and copper lead en bloc staining of zebrafish optic tectum. Image collected on a JOEL 1230 at 80 kV using a Gatan 967 slow-scan, cooled CCD camera at 60,000X. 70 nm thick section. Microwave processing, osmium tetroxoxide/osmid procedure for enhancing membranes, and copper lead en bloc staining. Procedure for specimen preparation available at http://www.stanford.edu/~redhair/JoAnn_Buchanan.