iiinova — where your digital self keeps evolving

Mathieu Preußner @mathpreu.bsky.social · 14/08/2026

For this #FluorescenceFriday 🔬 A glimpse into our latest work: Shroom3 influences pillar cell contractility and establishes a mechanical threshold for gill lamella stability. #Zebrafish ⚪ Pillar cell nuclei 🔴 Contractile apparatus More soon — multi-post thread coming! 🧵 🔗 doi.org/10.64898/202...

MIP of cryosection from adult gill arches showing a top view of a respiratory lamella stained with DAPI (white) and phalloidin (red), acquired using Machine Intelligent Structured Illumination Microscopy (MISIM)

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Mathieu Preußner @mathpreu.bsky.social · 20/03/2026

I don't really know😅 but I found this paper: www.sciencedirect.com/science/arti... Apparently they form "from the coalescence of short actin-filled precursor protrusions called pegs"

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Mathieu Preußner @mathpreu.bsky.social · 20/03/2026

Follow-up from last week’s #FluorescenceFriday 🐟✨ Took a closer look at the gill comb “tooth” — the actin microridges of the enveloping epithelial layer almost look like microscopic fingerprints, each with a distinct pattern #Zebrafish #DevBio #Microscopy #SciArt

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Mathieu Preußner @mathpreu.bsky.social · 13/03/2026

Just combed through my old data… et voilà: a tooth of the gill comb. 🐟✨ #FluorescenceFriday #zebrafish #DevBio #SciArt

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Mathieu Preußner @mathpreu.bsky.social · 13/02/2026

2/2 zooming in for a more detailed look on lamellae

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Mathieu Preußner @mathpreu.bsky.social · 13/02/2026

1/2 Happy #FluorescenceFriday 🔬 Another cryosection of a dissected zebrafish gill: ⚪Phalloidin 🔵DAPI

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Mathieu Preußner @mathpreu.bsky.social · 05/12/2025

This distal gill tip is giving full branchial art vibes for #FluorescenceFriday 🦓🐟 — who knew oxygen exchange could be this pretty. 🔴 kdrl:mCherry highlights the vasculature ⚪ fgf10b:nEOS marks the pillar cells #Zebrafish #DevBio #SciArt

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Mathieu Preußner @mathpreu.bsky.social · 14/11/2025

#FluorescenceFriday – Kidney Edition! Giving the gills a day off 😉 Cryosection of 5dpf old 🦓🐟 larvae showing: 🟡podocytes 🟢VitaminD-binding protein-GFP ⚪Phalloidin Notice how there’s no GFP signal in the pronephric duct — proof that filtration barrier is working perfectly #Zebrafish #DevBio

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Mathieu Preußner @mathpreu.bsky.social · 31/10/2025

Can't believe it — my first‑author paper is out and my image graces the cover of @dev-journal.bsky.social 🎉 Here, we reveal how early developmental programs shape and maintain #zebrafish gill architecture throughout life 🔗 journals.biologists.com/dev/issue/15... #FluorescenceFriday #LifelongDevSI

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Mathieu Preußner @mathpreu.bsky.social · 17/10/2025

For this #FluorescenceFriday 🔬 a cryosection of a dissected zebrafish gill, stained with phalloidin (orange) and DAPI (blue-ish). #Zebrafish #DevBio #Microscopy

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

15🧵 For those who made it this far... 👀 We’re not done with pillar cells. They’ve got a lot more to say — about mechanics, structure, and dynamics. More soon in our next paper. Stay tuned! 🧠🧪🔬 AGAIN! Big thanks to everyone involved—especially to @vlecaudey.bsky.social

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

14🧵 Gills offer a powerful model to study : 🩸 Angiogenesis 💨 Blood flow & pressure 🧠 Neural crest stem cells 🌿 Branching morphogenesis — all in vivo. Our work provides a detailed framework to explore these complex processes.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

13🧵 We quantified pillar cell numbers using: 🔬 ECI-based tissue clearing 📏 Isolation of single lamellae from filaments Then, with the IMARIS Spots Module, we extracted detailed spatial and quantitative data — giving us a precise map of pillar cell distribution.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

12🧵 Pillar cell number and lamella size showed clear developmental asymmetries — these also depend on: 📍 Whether the filament is medial or lateral 📍 Its position along the dorsoventral axis This structural asymmetry likely reflects different functional roles of filaments and lamellae.

F) Plot showing the direct comparison of PC number per lamella (red) with corresponding filament length (grey) in lateral (left) and medial (right) filaments.

(G) Direct comparison of the lamella surface of lateral (left) and medial (right) filaments in the three regions on the arch.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

11🧵 But endothelial cells don’t work alone. Lamellae morphogenesis depends on tight coordination between: 🔴Endothelial cells ⚪Pillar cells (neural crest-derived!)

(D) Differently mature lamellae in a 14 dpf kdrl:mCherry; fgf10b:nEOS larvae. nEOS-positive pillar cells (white) are already in contact with the tip cell of the OMC (red) at onset of OMC formation (wide arrowhead).

(E) Schematic describing the interplay of pillar cells and the OMC tip cell during lamellae outgrowth.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

10🧵 Now, lets talk more about lamellae 🍂 We examined the development of gill lamellae. It all started with an endothelial tip cell from the efferent filamental artery, which migrated across the lamella toward the low oxygen afferent side. ➡️ This forms the outer marginal channel (OMC)

(A) Overview of the gill vasculature in a 5.5 dpf larva (left). (A′) Digitally isolated third gill arch with close-up views of two medial filaments (dotted and dashed boxes) revealing tip cells of the outer marginal channel (OMC; pseudo-coloured in white) in emerging lamellae.

(B) Overview of the gill vasculature in a 5.5 dpf larva. (B′) Digitally isolated second gill arch with close-up views showing a fully closed OMC (pseudo-coloured in white, dashed box, upper panel) on a medial filament and a tip cell on a lateral filament (pseudo-coloured in white, dotted box, lower panel).

(C) Schematic illustrating OMC formation.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

Medial filaments were generally longer with more lamellae along most of the dorsoventral axis — except ventrally, where lateral filaments took the lead. The asymmetry reflects developmental timing: medial filaments form first dorsally, lateral ones ventrally — shaping function well into adulthood.

(A) First gill arch from 6- and 14-month-old fish cleared with ECi and stained with Concanavalin A. Medial filaments are pseudo-coloured in white and lateral filaments in red.

(C) Distribution of the medial and lateral filament length in the first gill arch along the dorso-ventral axis. Curves represent fitted LOESS model with s.e. (grey area). Each point represents a single filament.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

9🧵 This specific early gill developmental pattern sets the stage for adult gill architecture. We tracked filament and lamella number and distribution across the 4 gill arches between 3.5 and 14.5 dpf up to 6 month.

(A,D,G,J) Overview of the gill vasculature at the indicated time points (left panel) and the first gill arch digitally isolated from the overview with lateral (middle panel) and medial (right panel) filaments highlighted in white.

(B,E,H,K) Box plots showing the number of medial and lateral filaments for each arch.

(C,F,I,L) Plots displaying the number and distribution of lamellae per filament across the dorso-ventral axis of the gill arch. Curves represent fitted LOESS model with s.e. (grey area).

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

8🧵 But then something unexpected happened (4–5 dpf). Branching of the medial branchial artery marked a key symmetry-breaking event that separated how filaments formed dorsally vs. ventrally. 👇 In the ventral region (below MBA branch): 🔹 Lateral filaments sprout first 🔹 Medial filaments form later

FIgure showing pinching and subsequent detachment of the medial branchial artery (MBA) (dorsal) from the branchial artery (BA) (ventral). In the meantime the MBA bifurcates into the inner (IMBA; #) and outer (OMBA; *) medial branchial arteries. Subsequently the first ventrally formed medial and lateral filaments emerge (encircled arrowheads and arrows).

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

7🧵 In the dorsal area of the arch, medial filaments emerged first and extended the LBA by connecting to their neighbouring medial filaments. Only after this connection was made, lateral filaments emerged and fused with the LBA. ➡️ We used live imaging to show this formation in action.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

6🧵 Once the newly established lateral branchial artery (LBA) fused with the branchial artery (BA), the segment of the original BA, located above the fusion site, will be designated as the medial branchial artery (MBA).

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

5🧵 So when do gill filaments form? Using high resolution live-cell spinning disc microscopy, we mapped their onset. The first medial filaments appeared around 2.5 dpf. They sprouted from the branchial artery (BA) and began connecting to neighbours — forming the lateral branchial artery (LBA).

(A) Maximum intensity projection (MIP) from a 16-h timelapse of gill vasculature development in a 3 dpf embryo, shown at five time points. The final panel (24:00 h) was acquired 8 h after the timelapse ended. The left-most image shows all four gill arches, while the subsequent panels show only the digitally isolated first arch to highlight the emergence of the first three filaments (numbered arrowheads) and of the lateral branchial artery (LBA) (pseudo-coloured in white).

(C) Schematic of the onset of gill filament and LBA formation.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

4🧵 Let’s zoom in 🔍 To study filament morphology in more detail, we used two transgenic markers: 🔴 kdrl:mCherry — marks endothelial vasculature ⚪ fgf10b:nEOS — highlights pillar cell nuclei within the lamellae Big thanks to @fabianlab.bsky.social for the fgf10b:nEOS line

(C) Digitally isolated gill filament from an adult zebrafish expressing kdrl:mCherry in endothelial cells (ECs) (red) and fgf10b:nEOS in pillar cells (PCs) (white).
(D) Lateral view of an isolated filament in an adult kdrl:mCherry zebrafish.
(E) Schematic showing the vasculature in a pair of filaments. Red and blue vessels represent oxygen-rich and oxygen-poor blood, respectively.

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

3🧵 Quick primer: Zebrafish have 4 gill arches on each side with filaments. Each filament harbours several stacked lamellae: the site of gas exchange. Each lamella is encircled by the endothelial outer marginal channel (OMC) and supported by many pillar cells, which maintain the intergrity.

Schematic of an isolated gill rake (top left) and lamella (top right), illustrating the regularly organized pillar cells (PCs) and the outer marginal channel (OMC), and a cross-section (bottom) of a lamella showing erythrocyte flow within the vascular space bordered by PCs and ECs of the OMC. PVs are surrounded by two pavement cells (PVCs) above and below

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

2🧵 This curiosity-driven project started by sheer coincidence. While imaging the gills for a different scientific question, I noticed a consistent pattern: filament length varied along the dorsoventral axis. 🔴 Medial filaments (red) were longer than ⚪ Lateral filaments (white) —except ventrally.

(A) Schematic of the four gill arches of an adult zebrafish.

(B) Vascular network of a first gill arch isolated from a 3-month-old kdrl:mCherry fish and cleared using the CUBIC method, with the lateral hemibranch pseudo-coloured in white (right panel).

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Mathieu Preußner @mathpreu.bsky.social · 17/09/2025

1🧵 Excited to share my first PhD paper, published in @dev-journal.bsky.social What if fish gills —often overlook —hold secrets about development, patterning, and function? We uncovered how early patterning shapes adult gill architecture. journals.biologists.com/dev/article/... #DevBio #Zebrafish

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Mathieu Preußner @mathpreu.bsky.social · 05/09/2025

Big thank you to @biologists.bsky.social, @focalplane.bsky.social and @the-node.bsky.social for sending me the printed poster of my image from their imaging contest earlier this year! 🔬 It finally found a spot in my new flat — I couldn’t be happier to have this piece of science art on my wall❤️💙

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Mathieu Preußner @mathpreu.bsky.social · 11/07/2025

2/2 Also got a close-up where the expression pattern goes full-on pointillism Among others, fgf10b is expressed in gill pillar cells, that structure the vascular network within the lamella.

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Mathieu Preußner @mathpreu.bsky.social · 11/07/2025

1/2 🧬🎨 When gills do Pointillism! For this #FluorescenceFriday, here’s a dissected gill arch expressing nuclear fgf10b:nEOS — depth color-coded: blue for medial filaments, yellow for lateral ones. #Zebrafish #DevBio #Microscopy #Gills

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Mathieu Preußner @mathpreu.bsky.social · 20/06/2025

It’s a quill? A sea pen? No—it’s a gill filament! 🪶🪸🐟 Under the microscope, this fish gill structure looks just like a sea pen. Fascinating how nature keeps circling back to the same shapes. Want to learn how gills develop? 👉 www.biorxiv.org/content/10.1... #FluorescenceFriday #Zebrafish

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

9) Gills offer a powerful model to study angiogenesis, blood pressure, (NC) stem cells, and branching morphogenesis in vivo. Our work provides a detailed framework to explore these complex processes. We anticipate this resource will serve as a foundation for future functional & mechanistic studies

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

8) In adult fish no new filament are being added. Exisiting ones only increasae in their size

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

7) Pillar cell number and lamellar size reflect developmental asymmetries but are modulated by dorso-ventral position and filament identity (medial or lateral). Our findings suggest that the structural asymmetry correlates with functional roles of filaments and lamellae in optimizing gas exchange.

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

6) Additionaly we examined the development of gill lamellae, the sites of gas exchange, which arise through coordinated interactions between endothelial cells and neural crest-derived pillar cells.

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

5) Using live cell microscopy we showed that gill filaments form asymmetrically along the dorsoventral axis: dorsally, medial filaments emerge first and are longer; ventrally, lateral filaments form before medial ones. These early patterns predict adult gill architecture.

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

4) To examine filament morphology in greater detail, we combined kdrl:mCherry (red) with the recently described fgf10b:nEOS (white)-shoutout to @fabianlab.bsky.social -. kdrl:mCherry labeled the gill vasculature, while fgf10b:nEOS revealed the pillar cell nuclei within the lamellae.

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

3) kdrl:mcherry revealed a consistent medio-lateral asymmetry in filament length along the dorso-ventral axis: medial filaments were longer than their lateral counterparts (pseudo-coloured white), except in the ventral-most region of the arch where lateral filaments were longer.

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Mathieu Preußner @mathpreu.bsky.social · 06/06/2025

1) Branching morphogenesis is fundamental to animal development, shaping complex organs like lungs, kidneys, and vascular networks. Gills are another highly branched organ. Yet, the developmental processes behind gill formation in zebrafish remain poorly understood. #zebrafish #gills #microscopy

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Mathieu Preußner @mathpreu.bsky.social · 05/06/2025

If you’ve ever wondered how those intricate gill structures emerge—and how gills develop throughout a zebrafish’s lifespan—check out my new preprint! We dive into the development of gills and their vasculature in detail. Huge thanks to @vlecaudey.bsky.social for the support🐟 #zebrafish #microscopy

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Mathieu Preußner @mathpreu.bsky.social · 23/05/2025

🧬 #FluorescenceFriday Stepping away from 3D today to appreciate the architecture from within: a cryosection of a zebrafish gill filament, stained with phalloidin (bluish) and DAPI (yellowish), revealing the lamellar vascular network structured by pillar cells. #Zebrafish #DevBio #Microscopy

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Mathieu Preußner @mathpreu.bsky.social · 16/05/2025

🔬✨ Today for #FluorescenceFriday: A close-up of the dorsal part of the first gill arch in a mature zebrafish. The intricate vascular network supporting respiration, visualized using kdrl:mcherry. #Zebrafish #DevBio #Microscopy #Fluorescence #SciArt

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Mathieu Preußner @mathpreu.bsky.social · 25/04/2025

-A Gill's Secret Sidekick - A small, often-overlooked organ tucked behind the eye. In zebrafish, the pseudobranch arises from mandibular arch mesenchyme — the same region that forms jaws — and shares gene expression and developmental programs with true gills. 🔬 #FluorescenceFriday #zebrafish

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Mathieu Preußner @mathpreu.bsky.social · 11/04/2025

Gills just wanna have #FluorescenceFriday 🎵 Phalloidin reveals the beauty of the filament's distal tip in cleared gills of adult 🦓🐟 #microscopy #devbio #sciart

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Mathieu Preußner @mathpreu.bsky.social · 28/03/2025

In the mood for some gillspiration 🦓🐟 for #FluorescenceFriday ? Here, both endothelial reporters kdrl (yellow) and fli1a (white) highlight the four gill arches, showing several filaments and lamellae at 10 dpf. #microscopy #devbio #sciart

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