A Hypsibius exemplaris embryo grows here from one cell to a hatchling in about four days. Every early division is timed cell by cell from the measured lineage, and each stage arrives when the recorded embryos reach it: the column on the right checks all nineteen as they happen. The cells gastrulate, close into an epithelium and elongate by their own rules; then the body lays out its segments, grows limb buds, a pharynx, ganglia, claws and eyespots, turns in its shell and hatches. From elongation on, the body follows shape targets we built from the published stages. Cells are drawn packed, filling the shell as they do in the living egg. Next: every cell with its own membrane and cytoskeleton.
Levin et al. 2016, 60 single embryos sequenced one per half hour. Counts per million; each point is a different animal. All 429 genes →