#epithelia

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Sensory Forces

Organoids (lab-grown tissue models) grown on hydrogel with tuneable mechanical properties reveal the role of the extracellular matrix forces in guiding the formation of sensory epithelium – such as that involved in hearing in the inner ear

Read the published research paper here

Image from work by Mingyu Xia, Mingxuan Wu, Yuanrong Li and colleagues

State Key Laboratory of Fluid Power & Mechatronic Systems, Zhejiang University, Hangzhou and State Key Laboratory of Medical Neurobiology & MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Science Advances, November 2023

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🐦 Tweet 🐦

The lesser spotted squamous sparrow observed in a pap smear

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Histology is by expert cell twitcher @tina230986 [Insta]

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Reaching the Tip

Enterocytes, the cells lining the intestine that take up water, nutrients and minerals, migrate from the intestinal crypt to the tip of the finger-like projections called villi. Using an organoid system enriched for villus tip enterocytes, this study characterises the molecular changes that govern their unique features

Read the published research paper here

Image from work by Linda Berková and colleagues

Laboratory of Cell and Developmental Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in EMBO Reports, July 2023

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Creating Cavities

Even the most complex organs begin as clumps of cells. Developing their shapes requires careful organisation. Researchers now investigate by growing organ-like tissues (organoids) from mouse embryonic stem cells and using quantitative microscopy (pictured) to image their cell surfaces (white) and cell-cell boundaries (green). The organoids formed tissues called neuroepithelia using two mechanisms: fusing together two separate masses of epithelia (trans fusion) and fusing together two ends of the same epithelium (cis fusion). Organoid shape was determined by these rates of fusion. The team were able to control these rates by adding the chemical retinoic acid (RA). Over several days without RA (top), cis fusion dominated, resulting in each organoid forming one large fluid-filled cavity with multiple passages leading into the cavity from the outer surface. With RA, trans fusion dominated, leading to organoids with multiple cavities (bottom). Together, this model provides insights into how complex tissues self-organise.

Written by Lux Fatimathas

Image from work by Keisuke Ishihara and Arghyadip Mukherjee, and colleagues

Max Planck Institute for the Physics of Complex Systems (MPI-PKS), Dresden, Germany and Research Institute of Molecular Pathology (IMP), Vienna, Austria

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in Nature Physics, November 2022

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Neighbourly Dynamics

Tissue development is sometimes a little like origami – a flat sheet of epithelial cells folding and remodelling into a complex tissue. Researchers have long studied the 2D interactions of these epithelial cells with their neighbours during this elaborate process. Now they investigate their 3D interactions using light-sheet microscopy of growing embryonic mouse lung tissue in dishes, subsequent data analysis called 3D cell segmentation (pictured) and physical theories. They found the epithelial cells (top) had irregular 3D shapes and often changed neighbours, both as they grew and during the cell cycle as their nuclei (bottom) moved up and down. However, the cells still followed established mathematical laws and rules of movement within epithelial layers and throughout the full thickness of the tissue. This reveals that although 3D organisation in epithelia is complex, it still follows simple physical rules. These insights will help better model epithelia in health and disease.

Written by Lux Fatimathas

Image by Harold Fernando Gomez and colleagues

D-BSSE, ETH Zurich, Basel, Switzerland

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in eLife, October 2021

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Key principles of epithelial tissues:

Epithelial tissues comprise sheets of cells that are connected via intercellular junctions

Epithelial tissues are polar: The apical surface is "free," meaning it faces the external environment or the lumen of an internal passageway The basal surface attaches to the underlying basal membrane, which is a type of connective tissue

Some general functions of epithelial tissues include: Protection of underlying tissues from damage due to abrasion and/or dehydration Secretion Absorption

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[Source: Essential role for a novel population of binucleated mammary epithelial cells in lactation. Anne C. Rios et al (2016), Nature Communications http://dx.doi.org/10.1038/ncomms11400]

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Epithelial Cell Doh-mains

This figure from an old cell biology textbook shows the structural domains of epithelial cells and looks like Bart Simpson.

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