Fig. 3

Schematic representation of developmental stages observed. Information on formation of morphological structures combined from acetylated α-tubulin immunoreactivity and osmium tetroxide stained whole mount preparations (for reasons of clarity epidermal cilia in the aspect of view, as well as the cilia of the frontal epidermal invaginations, the nephridia, the stomodaeum, and the midgut omitted); top row: frontal view, bottom row: right lateral view. a 1-dpf, late gastrula, frontal epidermal invaginations. b 2-dpf, apical tuft formed, mouth opening shifted ventrally (Note the dotted lines in the bottom row indicating the uncertainty about the presence of an open connection between mouth and midgut). c 3-dpf, nephridia and pigmented eye visible. d 5-dpf, eye enlarges, frontal epidermal invaginations smaller. e 7/10-dpf, most advanced stage, no primordia of proboscis, anal opening, or blood vascular system visible. at: apical tuft, bp: blastopore, eci: epidermal cilia, fi: frontal epidermal invaginations, mg: midgut, mo: mouth opening, nep: nephridia, pe: pigmented eye