Fig. 8
Anatomy of the torus stage of Micrura sp. “dark.” a1-a2 and c1-c2 are confocal projections of larvae stained with phalloidin (white), and propidium iodide (orange). a1-a2 are transverse sections (from apical to vegetal), juvenile anterior is up. c1-c2 are frontal sections (from posterior to anterior, apical is up). a1. A 1.95 μm slab showing the developing proboscis (pb) and fused pairs of cephalic and trunk discs, forming the head (hd) and trunk rudiments (tr), respectively. a2. The same individual as in a1. A 1.95 μm slab showing the head and trunk rudiments fused around the gut, forming the characteristic toroid of juvenile tissue. The cerebral organ discs (cod) are closed off from the gut. Note the larval pore (pr), which is associated with the larval cirrus (not visible on this slab). b. A diagram summarizing a1- a2. c1. (outline of the gut omitted for clarity). A 1.95 μm slab (frontal view) showing the apical organ and trunk rudiment. c2. A 1.95 μm slab (frontal view) showing the proboscis rudiment, the cerebral organ discs closed off from the gut. d. A diagram summarizing c1-c2 (outline of the gut omitted for clarity). Scale bars 50 μm