Microscale imaging of cilia-driven fluid flow

Abstract

Cilia-driven fluid flow is important for multiple processes in the body, including respiratory mucus clearance, gamete transport in the oviduct, right-left patterning in the embryonic node, and cerebrospinal fluid circulation. Multiple imaging techniques have been applied towards quantifying ciliary flow. Here we review common velocimetry methods of quantifying fluid flow. We then discuss four important optical modalities, including light microscopy, epifluorescence, confocal microscopy, and optical coherence tomography, that have been used to investigate cilia-driven flow.

Three-dimensional, three-vector-component velocimetry of cilia-driven fluid flow using correlation-based approaches in optical coherence tomography

“…In the trachea, the airway surface liquid (ASL), which consists of the mucus layer and the periciliary layer, is known to be cleared in a tail-to-head fashion [35]. Because of the typically thin layer size (7 µm periciliary layer and 8-80 µm mucus layer) [1], imaging the ASL directly can be challenging. µOCT, a variant of OCT with higher spatial resolution, has recently been used to quantify ciliary dynamics and tracheal mucus velocity in swine trachea [36].…”

“…Ciliary flow is responsible for clearance of mucus from the respiratory tract, movement of cerebrospinal fluid (CSF) in the ventricles of the brain, determination of left-right patterning in the embryonic node, and movement of ova in the Fallopian tubes [1]. Because ciliary flow results from the shearing action of many cilia along a complex geometrical surface, ciliary flow lacks certain symmetries, such as unidirectionality and axisymmetry [2][3][4].…”

Adrenomedullin regulates the speed of oviductal fluid flow in cattle

“…Oviducts provide the optimal environment for sperm capacitation, gamete and embryo transports, and fertilization, which each contribute to successful pregnancy (Ellington, ; Gauvreau, Moisan, Roy, Fortier, & Bilodeau, ; Menezo & Guerin, ;). Oviductal fluid flow and smooth muscle motility transport gametes to the ampulla, where fertilization occurs, and the embryo to the uterus (Bennett, Watts, Blair, Waldhalm, & Fuquay, ; Halbert, Tam, & Blandau, ; Huang & Choma, ). Fluid flow within the oviduct is also important for sperm selection and guidance of spermatozoa to the egg (Miki & Clapham, ; Tung, Ardon, Fiore, Suarez, & Wu, ).…”

“…The oviduct has two types of epithelial cells, ciliated and secretory (Joshi, ; Uhrín, ). Each ciliated cell has 200–300 cilia (Raidt et al, ; Satir & Christensen, ) that beat continually and synchronously toward the uterus (Croxatto, ), generating unidirectional flow of fluids toward the uterus (Huang & Choma, ; Hunter, ). The flow rate is correlated with ciliary beat frequency (Noreikat, Wolff, Kummer, & Kölle, ).…”

Quantitative optical coherence tomography imaging of intermediate flow defect phenotypes in ciliary physiology and pathophysiology

“…1 Despite its importance, it is a poorly understood aspect of respiratory physiology. Severe dysfunction of cilia in conditions such as primary ciliary dyskinesia (PCD) is associated with impaired respiratory mucus clearance and recurrent pulmonary infections.…”