Development of Respiratory Tract Cilia in Fetal Rabbits Electron Microscopic Investigation

Abstract

Cilia develop in the respiratory tract of rabbits during the 22–28 days in utero. In the early, “pre-cilia” stages, cuboidal cells elongate and develop microvilli on their upper or luminal surface. A large number of basal bodies are produced in the cytoplasm between the nucleus and upper surface. The basal bodies migrate towards the apical surface and orient themselves properly with respect to the surface. Finally a cilium rises above each basal body. Throughout the respiratory tract, this same sequence of steps is followed during ciliogenesis, but the upper part of the airway develops its ciliated epithelium first. The nose is followed by the larynx, then the trachea and finally the bronchi.