Electron microscopic immunocytochemistry on retinal cryosections. Cryosections of formaldehyde-fixed retinas were treated with α-VMAT2 and α-VGAT antibodies conjugated to gold particles of different diameters. A, In this electron microscopic image, a synaptic ending situated in the most scleral stratum of the inner plexiform layer contains a cluster of negatively stained synaptic vesicles that are labeled by both 15 nm (VMAT2) and 10 nm (VGAT) gold particles. This ending belongs to a DAergic cell because, in C57BL/6J mice, only this amacrine cell type contains VMAT2⁺ vesicles. Note that gold particles of either diameter are scattered individually throughout the ending. In the center, however, two 15 nm particles and one 10 nm particle (double arrow) are very close to one another and apparently associated with a single vesicle. B, A cluster of LDCVs is labeled for both VMAT2 and VGAT. A pair consisting of a 15 and a 10 nm gold particle (double arrow) is associated with a single LDCV.