invaginace

Invaginace, or invagination, is a biological process in which a sheet of cells folds inward to form a pocket, groove, or tube that creates a hollow organ or cavity. The term derives from Latin invaginare, meaning to roll inward. Invagination is a fundamental morphogenetic mechanism in many animal embryos and during organ formation.

Cellularly, invagination is driven by changes in cell shape and adhesion. Apical constriction—where cells tighten their apical surfaces—causes tissue to bend inward. Other mechanisms include cell intercalation, convergent extension, and coordinated cell migration. The process is regulated by signaling pathways and cytoskeletal dynamics that coordinate force generation and tissue remodeling.

Major embryological examples include gastrulation, where regions of the embryo fold to form the archenteron and primitive gut, and neurulation, in which the neural plate invaginates to form the neural tube. In insects, invagination contributes to internalizing mesodermal precursors. Invagination also participates in organogenesis by forming glands or ducts through inward folding of epithelial sheets.

Clinical relevance: abnormal invagination can contribute to disease. In humans, intussusception is a classic example, where a segment of bowel slides into an adjacent segment, potentially causing obstruction and requiring prompt medical intervention.

Invagination is often contrasted with evagination, the outward folding of tissue. The concept is widely used in developmental biology to describe how a flat sheet becomes a three-dimensional structure through inward bending.