Cell movements

In involution, a single layer of cells curves under itself to form two layers. An invaginating sheet of cells pokes inwards at one point to make a lined cavity. Ingressing cells (blue) delaminate from a sheet of cells. Epiboly is a set of complex movements including intercalation (cells moving between each other), cells crawling, and cells changing shape that results in a sheet of cells covering a surface. Convergent extension is cell intercalation and cell elongation to turn a short/wide tissue into a long/narrow tissue.https://scholarlycommons.pacific.edu/open-images/1012/thumbnail.jp