Movie S4.

A single larva developing from late L1 stage up to early L4 stage (beginning vulval invagination). Only 1° vulval cells are expressing the EGL-17::CFP marker. In early L2 (approximately 400 minutes), EGL-17::CFP fluorescence manifests in P6.p, continually increasing in intensity. During L3, the 1° fated VPC undergoes two consecutive rounds of division, forming the 1 cell, 2 cell and 4 cell stage of vulva development. All motion visible results from growth as well as slight linear motion still possible on-chip, all of which can easily be removed through image registration. Images are shown at 30-minute intervals for a total of 34 hours.