Figure 2

Persistence of FITC-dextran in pilidia of M. alaskensis. All panels show larvae derived from zygotes injected with FITC-dextran; anterior left, apical up; cd = cephalic disc, la = lappet, st = stomach, td = trunk disc, bf = buccal funnel, br = buccal ridge. (A) Feeding pilidium, eight days old, before imaginal disc formation. Small dark zones developing in anterior and posterior axils (arrowheads); ( A’ ) Single section at a level which includes entire near-half ciliary band. (B) Pilidium with developing cephalic discs, 16 days old. Dark zones have spread from axils to cover nearly half the episphere; ( B’ ) shows the near surface only, and dashed lines indicate the unlabeled region of the ciliary band. (C) Another 16-day-old larva from the same cohort, in which both cephalic and trunk discs had formed (not visible); dashed outlines indicate the dark zones, that is growing regions of larval epidermis. ( C’ ) Projection of subsets covering the right and left halves of the buccal funnel, showing dark patches (arrowheads) both on the inner lappet surface, anterior and posterior, and around the stomach entrance. (D) 26-day-old pilidium, with two pairs of discs; more than half of the larval epidermis consists of dark (that is, post-embryonically proliferated) cells.