Cilia-driven flows in the brain third ventricle

Abstract

One contribution of 17 to a Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.The brain ventricles are interconnected, elaborate cavities that traverse the brain. They are filled with cerebrospinal fluid (CSF) that is, to a large part, produced by the choroid plexus, a secretory epithelium that reaches into the ventricles. CSF is rich in cytokines, growth factors and extracellular vesicles that glide along the walls of ventricles, powered by bundles of motile cilia that coat the ventricular wall. We review the cellular and biochemical properties of the ventral part of the third ventricle that is surrounded by the hypothalamus. In particular, we consider the recently discovered intricate network of cilia-driven flows that characterize this ventricle and discuss the potential physiological significance of this flow for the directional transport of CSF signals to cellular targets located either within the third ventricle or in the adjacent hypothalamic brain parenchyma. Cilia-driven streams of signalling molecules offer an exciting perspective on how fluid-borne signals are dynamically transmitted in the brain.This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.

Intercellular and intracellular cilia orientation is coordinated by CELSR1 and CAMSAP3 in oviduct multi-ciliated cells

“…Eggs are transported steadily against the direction of fluid flow from the infundibulum to the ampulla by directional movements of the cilia, which are coordinated both within individual cells and between cells. The flow of cerebrospinal fluid (CSF) in the ventricles also depends largely on the movement of cilia belonging to ependymal cells, but flow in the ventricles also shows a complicated pattern (Eichele et al, 2020;Faubel et al, 2016). Additionally, the direction of cilia is not always the same as the direction of the organ.…”

On the unity and diversity of cilia

“…Recent experimental and computational innovations have enabled increasingly detailed and quantitative visualization of these flows, which are highly dynamic, even in brain explants. Eichele et al [59] detail the types, alignment and putative transport functions of cilia existing in the ependyma. Over the course of evolution, nervous systems arose to coordinate ciliary locomotion over even longer distances, adding a new dimension to controlling ciliated structures [41,60].…”

Cumulative Damage: Cell Death in Posthemorrhagic Hydrocephalus of Prematurity

“…As the maturation process progresses, the cilia grow longer and the basal bodies align in a direction according to cellular polarity and propelled fluid motion [119][120][121][122]. The subsequent metachronic beating of these cilia tufts creates regular, directed flow patterns of cerebrospinal fluid circulation near the ependymal surface within each ventricle [70,[123][124][125][126][127][128]. The proper development and function of motile cilia on ependymal cells is crucial in maintaining fluid homeostasis within the CNS, and as such has critical implications in both brain development and function [129][130][131][132][133].…”