Fig. 3. Ciliogenesis in rat trachea. (A) The first visible stage in the acentriolar pathway is the appearance of dense granules (arrowheads). (B) Procentrioles (P) form around deuterosomes (arrowheads). (C) Mature ciliated cells. The procentrioles have docked with the apical membrane to become basal bodies (arrowheads) and have extended cilia (Ci). Scale bars (A) and (B)=200 nm; (C)=5 µm.