The influence of mesenchyme on the epithelial glycogen and budding activity in mouse embryonic lung developing in vitro.

Experiments have been performed to show the association of epithelial glycogen with budding activity, and their dependence on the nature of the associated mesenchyme. The bronchial mesenchyme associated with the tracheal epithelium induces the appearance of a tracheal bud where glycogen remains present after its removal from the rest of the trachea. The bronchial mesenchyme associated with the tracheal epithelium after the normal disappearance of glycogen, still induces the formation of an epithelial bud where glycogen is clearly demonstrable. The primary left bronchus completely ceases its budding activity when brought in association with metanephrogenic mesenchyme; glycogen is totally absent from the resting epithelium. The reassociation of the morphogenetically quiescent primary left bronchus with bronchial mesenchyme brings about resumption of budding activity and reappearance of the epithelial glycogen, showing normal bronchial distribution.