Fig. 8. Light microscopic immunohistochemistry using the anti-Papilio RBP in the retina of Peris rapae. (A) Transverse section of distal region of the retina. Both primary pigment cells (small arrowheads) and secondary pigment cells (arrowheads) were labeled. Photoreceptors (white arrowhead) were not labeled. Non-immune serum gave no labeling (inset). (B) Transverse section of the proximal region of the retina. The secondary pigment cells (black arrowheads) were labeled, but the photoreceptors were not (white arrowheads). (C) Longitudinal section around the basement membrane (BM). The tracheal cells (white arrowheads) were strongly labeled. Scale bars, 30 µm.