Fig. 5
Anatomy of the “pileus” stage of Micrura sp. “dark.” a-c, e1-e3 are confocal projections of specimens stained with phalloidin (a) or phalloidin (white) and propidium iodide (orange). a-c sagittal sections, apical plate up, anterior lobe (al) to the left. e1-e3. Transverse sections of the same individual (from apical to vegetal), anterior lobe is up. a. A 29.9 μm-thick slab showing the opening of the blastopore (asterisk) between the lateral lappets (lp), the anterior (al) and posterior (pl) lobes, the lumen of the gut (gt), and the ciliated band (arrowheads) spanning the lateral lappet. Larval ciliary cirrus (lc) visible underneath the posterior lobe. b. Same individual as in A, a 1.95 μm slab showing the apical plate (ap), the gut, and the juvenile rudiments (dashed outlines) inside: one of the cephalic discs (cd), proboscis rudiment (pb), dorsal rudiment (dr), one of the trunk discs (td), and one of the cerebral organ discs (cod). c. A 1.95 μm slab showing the axil (ax, dashed outline), the ciliated band terminating in the axil (arrowhead), cephalic disc, dorsal rudiment, trunk disc and the gut. d. A diagram (lateral view) summarizing A-C (outer outline of the gut omitted for clarity). Horizontal lines show approximate levels of the sections on e1-e3. e1. A 1.95 μm slab showing the proboscis rudiment, paired cephalic discs, gut and dorsal rudiment. e2. A 1.95 μm slab showing paired cephalic discs and trunk discs, and the gut. e3. A 1.95 μm slab showing paired cerebral organ discs invaginating from the gut. F. A diagram (apical view) summarizing e1-e3 (outer outline of the gut omitted for clarity). Scale bars 50 μm