Ciliogenesis in the human oviduct epithelium during the normal menstrual cycle

Ciliogenesis has been investigated in the human oviduct epithelium during the normal menstrual cycle. Both centriolar and acentriolar pathways were involved in the replication of basal bodies. The centriolar pathway, in which procentrioles generate with the aid of preexisting diplosomes, played a minor role in the human oviduct. In the acentriolar pathway, fibrous granules were the first structure which appeared in the course of ciliogenesis and they initially occurred in association with the Golgi apparatus or free ribosomes. Subsequently deuterosomes arose in the aggregates of fibrous granules or apart from fibrous granules, and then microtubules-containing procentrioles originated around deuterosomes. Newly formed centrioles migrated to the apical cytoplasm with accompanying deuterosomes, and ciliary shafts extended first at the periphery of the luminal surface of ciliogenic cells. Deuterosomes as well as fibrous granules were considered to be related to the rootlet formation. Replicaion of basal bodies and protrusion of ciliary shafts mostly occurred during the proliferative phase of the menstrual cycle; however, a small number of fibrous granules indicating the ciliogenesis were still observed in some ciliated cells during the secretory phase. Ciliogenic cells in early stages of ciliogenesis contained secretory granules-like vesicles in the apical cytoplasm, suggesting that the ciliated cells are differentiated from secretory cells in the late secretory phase on demand.