Fig. 3.

Hemilineage cell clusters and SAT neuropil entry points migrate away from each other during metamorphosis. (A) Cartoon depiction of the behavior seen in secondary lineages containing hemilineages. Hemilineage cell body clusters (CC, shown as spheres) and their corresponding axon tracts initially form adjacent to one another as seen at the late larval stage (L3). By adulthood, many hemilineages completely separate (CCs and HSATs) to form morphologically distinct elements (generically termed as HLα and HLβ, shown in orange and green, respectively). The extent to which hemilineages migrate apart varies between lineages. ((B)–(G)) Metamorphosis of the hemilineages of the DPLl2/3 secondary lineages. (B) and (C) are z-projections of confocal sections of single brain hemispheres containing GFP-labeled DPLl2/3 neuroblast clones, induced in the early larval period and fixed in the late larva (B) or adult (C). Neuropil (in purple) is labeled by N-Cadherin. ((D)–(G)) Z-projections of contiguous confocal sections of BP106/BP104-labeled brains (BP106 in (D)–(E); BP104 in (F) and (G)). Confocal stacks used in (B)–(G) were digitally rotated 90^d to show the DPLl2/3 lineages from a lateral view. ((B), (D)) At the L3 and early pupal stage, DPLl2/3 appears as a pair of cell clusters (CC) whose axons come very close to each other and form a single SAT. This SAT splits into a posterior ventral (HSATp) and an anterior–dorsal (HSATa). These hemilineage tracts extend around the dorsal and lateral surfaces of the growing superior lateral protocerebrum (SLP) compartment during metamorphosis. ((E)–(G)) As the SLP grows ((E), P24; (F), P48; (G), adult), the hemilineage clusters HLa and HLp of the DPL2/3 lineage move away from each other. From P48 onward the clusters and HSATs are completely separated. Scale bar: 50 μm ((B)–(G)).