Fig. 5.

Morphological appearance of a NF stage 37 control larva before (A) and after fixation and acridine orange staining according to Zucker et al. [51] (B, C), with the corresponding histological sections (D, D’, E, E’).

A: Lateral view of a control larva with normal phenotype. Note the well-developed eye (*). Magnification 10 × .

B: Lateral view of a control larva with normal phenotype stained with acridine orange. Note the eye pigment circularly positioned and the centrally positioned crystalline (*).Magnification 40 × .

C: Frontal view of a control larva with normal phenotype stained with acridine orange. Note the round-opened stomodeum (s) and the forebrain bulges (t). Magnification 40 × .

D: Dorsal section of a control larva. Note the optical nerve (>) and the eye structure with centrally positioned crystalline and retinal layer already differentiated (*). Magnification 100 × .

D': Detail of the eye. Note the crystalline with different layers (*) and the regularly organized retinal layers (>). Magnification 400 × .

E: Ventral section of a control larva. Note the well-introflexed stomodeum (>>). Magnification 100 × .

E': Detail of E. Note the stomodeal ectoderm (black >) and the pharyngeal endoderm (red >) which are about to merge. Magnification 400 × .