Einstülpungen

Einstülpungen is a German term used in biology and related disciplines to describe the inward folding of a structure, resulting in an invagination or pocket. The word derives from stülpen, meaning to tuck in, with the noun suffix -ung.

In embryology and anatomy, Einstülpung refers to processes in which cell layers fold inward. A classic example is invagination during gastrulation, where portions of the blastula fold inward to form the archenteron and establish the germ layers. Likewise, epithelial sheets can invaginate to form glandular structures or ducts, creating pockets or deeper recesses within tissues.

In medicine, the concept of inward folding is encountered as invagination of tissues. A well-known clinical example is intussusception, in which a segment of a hollow organ telescopes into an adjacent segment. In German medical writing, invagination-like processes may be described using Einstülpungen or related terms, depending on context.

Beyond biology, the term can appear in other fields to denote inward folding of surfaces or materials, producing pockets, recesses, or folded features. The core idea across disciplines is the same: an outward surface or layer folds inward, altering the morphology and sometimes the function of the structure.

Overall, Einstülpungen serves as a general descriptor for inward folding phenomena, bridging terminology across biology, medicine, and applied sciences. It emphasizes the morphological outcome—the formation of invaginations—rather than a single specific mechanism.