Figure 4

A proposed sequence of P. pacificus pre-hatching development based on the current study and previously published data [6],[9]. Eggs are typically laid at the two-cell stage (A). Elongation during late-stage embryogenesis includes 2-fold (B), and 3-fold (C) embryos. Stage 1 juvenile (J1) cuticle synthesis is likely complete by the end of elongation (timing extrapolated from [8]) and marks the beginning of J1. Typical morphological features and associated behaviors found in L1 C. elegans occur in the pre-hatching J1 P. pacificus. Lethargus is defined by a lack of movement and formation of a buccal cap (D, E, white arrowhead) and is followed by ecdysis (F). Black arrowheads show J1 cuticle just before ecdysis in Ppa-mlt(csu28) (F). Worms reach the second juvenile stage just prior to hatching (G, H). White arrow (H) shows the remains of the J1 cuticle. Scale bars = 25 μm.