Fig. 4
From: Photoreceptor genes in a trechine beetle, Trechiama kuznetsovi, living in the upper hypogean zone
The internal structure and nerve tissue of T. kuznetsovi head. A Transverse section of a compound eye, dorsal is up. Scale bar indicates 20 µm. CO, cornea; R, putative photoreceptor cells; OR, ocular ridge. B Dorsal view of dissected head. Nerve tissue was stained with methylene blue solution. Scale bar indicates 0.5 mm. CE, compound eye; NB, nerve bundle; BR, brain (supraesophageal ganglion)