In Tribolium, the established morphological staging system (Biffar and Stollewerk, 2014) with respect to early neurogenesis has 15 stages, termed NS1 to NS15. (A, B) From NS3 to NS5, the neuroectoderm is still a flat sheet of cells. (C) At NS7, the labral and stomodeal buds have formed (arrow, white arrowhead). (D) At NS11, the brain grows thicker and contains an increased number of cells. (E, F) From NS13 onwards, the brain hemispheres become an oval shape and grow. (G) At NS15, the brain hemisphere shows a pear-like shape. All planes are dorsal view. (H) Tc-ase-RNA exonic probe marks cytoplasm. (I) Tc-ase-RNA intronic probe marks only nuclei, which allows cell identification.