basalbody

Basal bodies are cylindrical organelles that organize the formation of cilia and flagella. In most eukaryotic cells with cilia, a basal body is derived from a centriole and serves as the base from which the ciliary axoneme grows.

Structure: A basal body is similar in structure to a centriole, typically comprising nine triplet microtubules arranged in a ninefold cylinder. At the distal end it bears transition fibers and distal appendages that anchor the organelle to the plasma membrane and form the ciliary gate.

Function: It nucleates and anchors the axoneme, shapes the ciliary membrane, and organizes the transition zone for selective entry into the cilium. Basal bodies also act as microtubule-organizing centers during cell division, with the mother centriole able to convert into a basal body to initiate ciliogenesis in daughter cells.

Biogenesis and docking: Basal bodies duplicate once per cell cycle. The docking process to the membrane involves distal appendages; the transition zone forms the selective barrier that regulates traffic into the cilium.

Variation: Some protists and algae contain multiple basal bodies or complex basal apparatus. In many higher plants, cilia are absent, and centrioles/basal bodies are reduced or absent, whereas in ciliates basal bodies organize extensive ciliary systems.

Clinical relevance: Defects in basal body function or ciliogenesis can lead to ciliopathies such as primary ciliary dyskinesia and related developmental disorders.