Fig. 7.

Light responses and tracer coupling of knotty type 2 amacrine cells in Macaca fascicularis retina. (a) Light responses were recorded with intracellular electrodes from a dark-adapted knotty type 2 amacrine cell. Stimuli were full field, 500 nm, and 500 ms in duration. Stimulus intensities ranged from 17.8 (log₁₀ I = −4) to 1.78 × 10³ (log₁₀ I = −2) photons/µm²/s. (b) Under these conditions, Neurobiotin injected into one knotty type 2 amacrine cell spread to 123 neighboring amacrine cells of the same morphological type. This image is a projection of fourteen 1-µm optical sections. Scale bar = 20 µm. (c) This is a single 2-µm optical section through S2 of the IPL. Neurobiotin-injected knotty type 2 amacrine cell dendrites have numerous varicosities (arrows). (d) This is a single 0.5-µm optical section through S2 of the IPL. PV++ amacrine cell dendrites and varicosities in midperipheral retina (5–10 mm from the fovea) are very similar morphologically to the knotty type 2 amacrine cell dendrites. Scale bar = 10 µm.