infoldings

Updated: May 24, 2025

Similarly is it with the organs for smelling and hearing. These, too, begin as sacs formed by infoldings of the epidermis; and while their parts are developing they are joined from within by nervous structures which were themselves epidermic in origin. How are we to interpret these strange transformations?

Herbert Spencer - Essays: Scientific, Political, & Speculative, Vol. I

The bronchial tubes are the tree-like branches of the trachea, and extend to the air-cells themselves, which may be considered as built up around them in some such fashion as a toy balloon on its wooden stem, but with many infoldings, etc.

Wesley Mills - Voice Production in Singing and Speaking: Based on Scientific Principles (Fourth Edition, Revised and Enlarged)