Fig. 2. (A–D) Confocal image of the three-dimensional topography of the eyestalk and brain CRY immunoreactivity of P. clarkii at two times of day. All the images are optical sections of whole-mount preparations. (A) MT-HB complex cells expressing CRY at 03:00 h. The hemiellipsoid body shows a cluster of cells expressing a strong CRY immunoreaction; an immureactive cell apparently located in MT seems to branch towards the HB (small arrows). Note the protocebral tract (PT) expressing a dim immunoreaction. (B) MT-HB complex at 19:00 h, showing low immunoreaction. (C) Protocerebrum at 03:00 h; note the lack of immunoreactive signal at this hour. (D) Neurons of the protocebral anterior medial cluster (AMC) expressing strong CRY immunoreactivity at 19:00 h. Scale bars, 100 µm. (E) Fluorescence micrograph of a histological section showing the cytoplasm of some cells of the protocerebral anterior medial cluster (AMC) expressing CRY immunoreactivity at 11:00 h. Scale bar, 20 µm. See text for explanation.