Functions of Centrioles and Basal Bodies

The Contrioles and basal bodies are involved in mitosis, in microtubule generation, in ciliogenesis and in the formation of tail fibers in spermatozoa

1. Role in mitosis. The centrioles form the mitotic poles in higher animals. One view holds that the centrioles are involved in spindle formation. However, it has been shown that the spindle fibers do not arise from the centriole, but rather from plaques or corpuscles near the centriole. The role of centrioles in forming the mitotic pole is considered to be a secondary adaptation. Centrioles are absent in primitive cell types and in the cells of higher plants.

2. Microtubule generation. Microtubules (which form the spindle) have been observed in the cytoplasm during mitosis. Nonmitotic microtubules also occur. The microtubule generators (MTG). These plaques have been found in association with the nuclear envelope, the kinetochore of chromosomes, and near the basal bodies and the centrioles.

3. Ciligenesis. The primitive function of the centrioles seems to have been the generation of cilia and flagella, the primitive locomotory organelles of the eukaryotes. Both members of a pair of centrioles can give rise to cilium. Usually, however only one of them forms the cilium. Cilia and flagella always develop in the presence of basal bodies. The basal bodies acquire a basal plate, and the cilium then develops distal to the basal plate.

4. Sperm tail formation. In spermatozoa one centriole of a pair gives rise to the tail fibre. The structure of the tail fibre closely resembles that of the cilia and flagella.