Figure 1

Persistence of embryonically-expressed GFP in pilidia of M. alaskensis. All panels show larvae raised from zygotes injected with EMTB-3xGFP mRNA, anterior left and apical up. Note that in small-volume unstirred cultures, developmental rate is slower compared to times reported by Maslakova [14]. Left panels of (A) to (C) show transmitted light image, right panels show GFP fluorescence. Regions of reduced GFP fluorescence are attributed to cell division. (A) Young pilidium, 11 days old, imaginal discs not yet invaginated. Small dark patches have appeared in the axils (arrowheads) anterior and posterior to the lateral lappets (la). st = stomach. ( A’ ) Single confocal section through posterior axil (corresponds to dashed outline in (A); extent of the dark patch indicated by dashed line. (B) 21-day-old larva with cephalic and trunk discs (cd, td); dashed lines indicate the extent of the dark axillary regions within the larval primary ciliated band. Large dark patches (outlined in ( B’ ); near-surface projection) include the axils and nearly half of the episphere. ( B” ) Projection of the sections through the buccal cavity; arrowhead indicates dark zone near stomach entrance. bf = buccal funnel, br = buccal ridge. (C) 34-day-old torus-stage pilidium. Only small patches of the lappets (la) and the apex, the anterior and posterior lobes (arrowheads), and about half the buccal funnel, retain label; ( C’ ) shows near-surface projection. (D) Magnification of near-side lappet from C. (E) Magnification of apex and apical organ (ao) from (C). Innermost whorls of cells in the apical organ retain label, as seen on a medial slab through the apical organ ( E’ ), while peripheral cells of the apical organ are dark.