Fig. 1. Medullar neuroblast development. All images are of L3 stage unless otherwise noted. (A) Schematic of central nervous system. ED, eye disc; OL, optic lobe; VNC, ventral nerve cord. (B) Schematic of the optic lobe (ventrolateral view). Lamina neurons (La, gray), NE cells (blue), medulla NBs (light pink) and central brain (CB) are shown. (C) Schematic horizontal section of the optic lobe (section of blue plane in B). Lamina neurons (gray), NE cells (blue), medulla NBs (magenta), ganglion mother cells (GMCs, yellow), medulla neurons (orange), lamina furrow and R axons (R1-6 terminate in the lamina, while R7 and R8 project their axons through lamina to medulla) are shown. Cells located lateral most in the NE differentiate into lamina neurons (red arrow). (D) Confocal microscopic image of the optic lobe immunostained for lamina neurons (Dachshund, Dac, gray), NE cells (tkv-lacZ, blue) and medulla NBs (Dpn, magenta). (E,F) Lateral view (E) and horizontal section (F) of the optic lobe. Lamina neurons (Dac, white), NBs (Dpn, magenta), lobula neurons (Elav, yellow in E) and medulla neurons (Elav, yellow in F) are depicted. (G-I) The swath of NBs (Dpn, magenta) widens and the expanse of NE cells (Tailless, Tll, blue) decreases as the optic lobe matures. Optic lobe of early- (G), mid- (H) and late- (I) stage larvae. Tll is expressed in NE cells and lamina neurons. (J) Schematic of NB differentiation in G-I.