Pattern of per-expressing cells in a per⁺ BG transgenic adult at ZT21. This male carried the BG construct heterozygous with a balancer chromosome (TM2; see Materials and Methods) and was stained with anti-β-GAL antibody. A, The open arrowpoints to LN_d (relatively dorsal LNs; see Ewer et al., 1992). Scale bar, 25 μm B, High-magnification view ofA; four to five LN_d (diameter, ∼6 μm) lie close together; arrowheads point to glia in the cortex, adjacent to the neurons, and to glia bordering the medulla. Scale bar, 12.5 μm. C, A large oval cell of the LN_v group (large arrow); the smaller arrow points to four neurons of smaller diameter (∼6 μm).D, Higher magnification of C;arrowheads point to glial cells at the outer rim of the medulla and to glia in the second optic chiasm. E, DNs.F, Higher magnification of E, showing two overlapping DNs present in this section (diameter, ∼8 μm); thearrowhead indicates cortical glia. G, PR staining (left part of the image); thearrowheads point to glia in the lamina and in the layer between the PRs and lamina. Scale bar, 8 μm. H, Staining in the cardia. Magnifications in C,E, and H as in A; inD and F as in B.