Fig. 7. Distribution of HA immunoreactivity in the crayfish eyestalk. (A) Schematic representation of a dorsal view of the eyestalk and the relative position of HAergic like single neurons. LG, lamina ganglionaris; ME, medulla externa; GS, sinus gland; MI, medulla interna; MT, medulla terminalis; HB, hemielpsoidal body; ON, optic nerve. (B,C) FITC fluorescence for HA immunoreactive neurons observed by confocal microscopy; image compositions were done by merging 200 slides (1 µm section thickness). Scale bars, 20 µm.