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Functions of the Kidneys and Functional Anatomy
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
All the tubular epithelial cells except the intercalated cells in the distal tubule have a non-motile cilium, which acts as a flow rate sensor and chemoreceptor. The cilium detects changes in flow and content of tubular fluid and activating of calcium-dependent pathways that control cell function, as well as differentiation.
Bardet−Biedl Syndrome
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Located on the surface of different types of cells, cilia are the tiny hair-like structures (either motile or immotile) that utilize an architectural element known as basal body to anchor to a cell. Possessing central microtubule pair necessary for ciliary mobility, motile cilia propel fluid (e.g., mucus) through the local environment and assist in cell motility. Immotile (primary) cilia have unique 9 + 0 structure with nine microtubule triplets arranged in a circle with an outer membrane, and participate in cell signaling, left-right asymmetry, tissue formation, and homeostasis. In the eyes, rod and cone photoreceptor cells of the retina are known to utilize their immotile cilia for light-perceiving function [5].
Recording Ion Channels in Cilia Membranes
Published in Jinghua Hu, Yong Yu, Polycystic Kidney Disease, 2019
Leo C.T. Ng, Amitabha Mukhopadhyay, Thuy N. Vien, Paul G. DeCaen
Through the single lens of a homemade microscope, Antonie van Leeuwenhoek visualized the incredibly tiny feet of “animalcules.” The function of these beating motile cilia for locomotion of protists in pond water was obvious to van Leeuwenhoek.1He also observed motile cilia and flagella in human cells, noting that their undulations may move fluid or propel the sperm. A few hundred years later, embryologist Alexander Kowalevsky identified single cilia projecting from a variety of vertebrate cells.2,3 These “primary cilia” are immotile and are far more widespread than the motile cilia types within our organ systems. Besides motile and primary cilia, “sensory cilia” make up the third and most structurally diverse cilia type. Sensory cilia, as their name implies, are found in sensory tissues such as olfactory neurons and photoreceptor cells. In general, sensory and primary cilia are thought to function as cellular antennae—receiving and integrating stimuli (chemical and other) through the activation of molecular effectors such as G protein-coupled receptors (GPCRs) and ion channels which are concentrated in these projections.4,5 However, beyond fluid motion and motility, some evidence suggests that motile cilia may also carry out a sensory function for cells.6 Thus, there might be considerable functional overlap between these classifications of cilia. Below, we will discuss the structural, functional, and component differences among these three cilia types.
CT imaging features of paranasal sinuses in children with primary ciliary dyskinesia
Published in Acta Oto-Laryngologica, 2022
Huiying Lyu, Zhuoyao Guo, Chao Chen, Bo Duan, Zhengmin Xu, Wenxia Chen
Cilia are highly conserved organelles that can be divided into four types: 9 + 2 motile cilia, 9 + 0 motile cilia (nodal cilia), 9 + 2 non-motile cilia (primary cilia), and 9 + 0 non-motile cilia. The motile cilia are abundant in the respiratory tract, the Fallopian tubes, the deferent ducts, and the brain ependyma. Motile cilia are essential for mucociliary clearance and transport of fluid. The nodal cilia plays a vital role in establishing left–right body orientation during early embryonic development. Abnormalities in nodal cilia can lead to laterality defects that include situs inversus, heterotaxy, or dextrocardia that may be associated with congenital heart abnormalities. The underlying cause of PCD is mutations in genes encoding structural and/or functional proteins of the cilia. To date, over 50 PCD genes have been identified [13,14].
Investigation of CEP290 genotype-phenotype correlations in a patient with retinitis pigmentosa, infertility, end-stage renal disease, and a novel mutation
Published in Ophthalmic Genetics, 2020
Madeline Williamson, Elias Traboulsi, Meghan DeBenedictis
The CEP290 gene located at chromosome 12q21.32 encodes a centrosomal protein called nephrocystin-6 (NPHP6) that is important for ciliary assembly and function. Insufficient or dysfunctional motile and non-motile cilia may affect multiple organ systems and result in a wide range of organ abnormalities leading to such problems as blindness, deafness, chronic respiratory infections, renal disease, heart disease, and infertility. Due to the varied functions of cilia in humans, biallelic mutations in CEP290 lead to a phenotypic spectrum that spans isolated retinal problems as in Leber congenital amaurosis, to a number of systemic disorders including Senior-Loken syndrome (SLS), Joubert syndrome, and Meckel-Gruber syndrome (1). Although survival of rod and cone photoreceptors requires CEP290, the precise function of CEP290 has not been clearly identified and the mechanisms leading to photoreceptor death remain unknown.
A Stargardt disease-like phenotype in GAS8-related primary ciliary dyskinesia
Published in Ophthalmic Genetics, 2022
Human cilia are complex hair-like organelles that can be broadly categorized as motile or non-motile and contain a tubulin-based axoneme (1). Only certain specialized cells that propel mucous or fluid along their surfaces have motile cilia. In contrast, most human cells contain a non-motile cilium. Features that distinguish motile from non-motile cilia include a central pair of microtubules interior to the ring of 9 doublets (“9 + 2” structure) and an axonemal dynein complex that allows motility (1). Also, as opposed to motile cilia, non-motile cilia are often shorter and may be intracellular without projection beyond the cell surface (1).