Figure 2. Staging and mounting embryos.

(A) Assembled embryo collection cage. (B–B’) Collection plates before (B) and after (B’) embryo collection. (C) Zoom in to an embryo collection plate; embryos are mixed with yeast paste and still have chorionic membrane. (D) Zoom in to an embryo basket, after collecting dechorionated embryos. (E–E’) Embryos aligned in an embryo collection plate, with anterior up and dorsal facing the camera. The shape of the yolk allows staging of the embryos. From left to right: first embryo is in stage 13; the yolk looks like an inverted heart. Second embryo is a stage 16 embryo; the yolk has a two lobed appearance due to folding of the midgut. Third position is an unfertilized egg. The yolk is irregular and off centered, and the rest of the egg is more transparent relative to the other embryos. The fourth embryo is stage 15; the midgut has begun to fold. The last embryo is stage 14; the yolk seems more condensed compared to stage 13 but is more distended than stage 15. (F) All-at-once mounting method. The imaging plate is carefully brought towards the aligned embryos so that they stick to the glass (1). In the same movement, the plate is then moved upwards (2) with the embryos glued to the plate. (G) Embryos attached to the glass after the imaging plate was approached to the agar block.