Mathieu Preußner

First 24 hours of embryonic development in 9 different animal species: (From left to right) Zebrafish, Sea urchin, Black widow spider, Tardigrade, Sea squirt, Comb jelly, Parchment tube worm, Roundworm, Slipper snail. Credit to @tessamontague.bsky.social & Zuzka Vavrušová. #ZebrafishZunday #devbio 🧪

This microscopic freshwater organism, Limnias malicerta, is a rotifer, recognized by its rotating wheel-like structures. It uses spinning cilia on its head to swim and capture tiny food like algae and bacteria.

Original post

A cell videoed through a microscope. DNA in the nucleus (cyan), mitochondria (yellow), and the actin filament cytoskeleton (magenta) are shown. #CellBiology

Congratulations Maik, so well deserved! and such a nice thread!! Looking forward to meet+hear you next week!

Congratulations! 🎉👏
Sadly I’ll miss the meeting, but I hope you have a great celebration. Well deserved! 🎊

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I am truly honored to receive the Hilde Mangold Award from @gfeev.bsky.social!

Mangold’s classic transplantation experiments transformed developmental biology and our understanding of self-organization. I am grateful to be associated with this legacy!

Bridging the gap (axonal regeneration in zebrafish recorded live!)

Blood vessel development and lumenization in a zebrafish embryo. Credit to Dr. Kazuhide Shaun Okuda @latrobeuni.bsky.social. #ZebrafishZunday 🧪

PEOPLES OF EARTH: BE PREPARED 🧪

😍

🔗 to paper: journals.biologists.com/dev/article/...

#ZebrafishZunday: Valentine's Day Edition ❤️ Beating heart of a transgenic zebrafish embryo. Credit to @zebrafish007.bsky.social. 🧪

I see what you mean 😁

These are intracellular, actomyosin-rich contractile apparatuses of gill pillar cells— and if all goes well, you might be able to read much more about them in an upcoming publication😉

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

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

Experimental #FluorescenceFriday today : This is the head of a tiny fig wasp imaged in 3D with confocal microscopy, color gradient indicates depth. Cross your eyes and let the images overlap for a cool 3D effect!
#Sciart

Special Issue The Extracellular Environment in Development, Regeneration and Stem Cells Guest Editors Alex Hughes (University of Pennsylvania) Rashmi Priya (The Francis Crick Institute) Submission deadline: 1 March 2026. Development call for papers. Image of magenta and teal cells in a jawbone.

Submit your latest research to our upcoming special issue – The Extracellular Environment in Development, Regeneration and Stem Cells

Guest Editors: Alex Hughes (@hugheslabpenn.bsky.social) & Rashmi Priya (@rashmi-priya.bsky.social)

Deadline: 1 March 2026

journals.biologists.com/dev/pages/ex...

🔬Join our #ReproductionMS seminar with Dr.
@maikbischoff.bsky.social on "Coiling a Duct: How Mesenchymal Cells Sculpt Male Reproductive Organ Architecture" this Wednesday, 11 February 12pm CET. DM for Zoom details.

This week’s #MicroscopyMonday features a confocal microscopy image that shows cell nuclei in zebrafish skin (blue) and different types of skin ionocytes (magenta, orange). 🔬 (Piotrowski Lab)

Not something you see in textbooks very often: tripolar mitosis.

Job alert! 📣 I’m looking for a research assistant to join my new team @idrm.ox.ac.uk

Were using #zebrafish to understand gene-environment interactions that shape the heart 🫀generate natural diversity 🐸🐭 and contribute to congenital defects ❤️‍🩹

Full info below, and please share! 🫶🏻

bit.ly/467TO0M

Christian Helker @unimarburg.bsky.social and co-workers show that apelin signaling acts as a molecular switch between endothelial and hematopoietic #stemcells.

link.springer.com/article/10.1...

Highlight by @labmonteiro.bsky.social @unibirmingham.bsky.social

link.springer.com/article/10.1...

Maximum intensity projection showing dorsal vasculature of the first gill arch of a CUBIC-cleared adult kdrl:mCherry zebrafish. Fluorescent signal was pseudocoloured using the PBIYC lookup table in ImageJ. Analysis of this endothelial reporter enabled detailed mapping of gill vascular development and revealed distinct medial and lateral filament types. Credit text to the journal Development. See Research Article by Preußner et al. https://doi.org/10.1242/dev.204984

Adult zebrafish gill vasculature. Credit to @mathpreu.bsky.social. #ZebrafishZunday 🧪

Wow 😍
Thanks for sharing 🤝

Fig. 1. Animal cap assay and sandwich method as in vitro induction systems. In amphibians, a blastocoel cavity clearly forms inside the animal hemisphere during the blastula and early gastrula stages. The cap-like portion lining the roof of the blastocoel cavity is the animal cap. This region consists of a sheet of pluripotent cells, organized into one or several layers. In the animal cap assay, the animal cap was treated with a physiological saline solution containing inducing factors and then cultured. Depending on the type, concentration, and duration of exposure to the inducing factors, animal caps can differentiate into various cell types. In contrast, the sandwich method, involves culturing the inducer source in between two animal caps. In this technique, the sources of induction can include the dorsal lip of the blastopore (organizer), adult tissues, pelletized soluble factors, or animal caps pretreated with soluble factors. In this figure, activin is used as an example of an inducing factor.

Fig. 12. Summary of the in vitro induction system using activin as an inducing factor. This in vitro induction system utilizes activin and retinoic acid as inducing factors to treat animal caps, employing techniques such as animal cap assay, dissociation/reaggregation protocol, and the sandwich method. By applying these methods, various levels of self-organization can be replicated and controlled in vitro, ranging from lower-order cell differentiation to higher-order tissue differentiation, organogenesis, and even the formation of fundamental body plans. Abbreviations: Dorsal [D], ventral [V], and retinoic acid [RA].

Fig. 11. Formation of embryoids by artificial activin concentration gradients. To create embryoids, animal caps were prepared through treatment with low (0.5–1 ng/ml), intermediate (5–10 ng/ml), or high (50–100 ng/ml) concentrations of activin. These three types of activin-treated animal caps were then sequentially arranged and cultured with untreated animal caps. After 3 days of culture, embryoids with distinct head and trunk-tail structures were formed (A). Histological sections revealed differentiation into head tissues, such as the cement gland [cg] and eyes, and trunk-tail tissues including the ear vesicle [ev], brain [br], notochord [not], muscle [mus], and gut (B). When newt embryos are used in similar combination cultures, neural plate structures forming the brain [white arrow] and axial structures forming the trunk-tail regions [black arrow] are sometimes observed (C).

Fig. 7. In vitro heart formation and in vivo transplantation experiment. When treated with a high concentration of activin, the animal caps of Xenopus embryos did not differentiate into heart tissue. However, if the animal cap dissociates into individual cells before activin treatment and then reaggregates, it forms a beating heart [arrow] with 100 % efficiency (A). This heart expresses differentiation marker genes, such as Nkx2.5, GATA-4, Tbx5, MHCα, TnIc (cardiac troponin I), and ANF, none of which are expressed in an animal cap treated with activin alone, without dissociation/reaggregation (B). Electron microscopy reveals the presence of intercalated discs [id] specific to the cardiac muscle, along with visible mitochondria [m] and Z-bands [z] (C). When the reaggregated heart tissue is orthotopically transplanted into the cardiac primordium of a neurula-stage embryo, it integrates without rejection and continues to beat (D), although it does not persist through host metamorphosis. In contrast, when the reaggregated tissue is ectopically transplanted into the ventral region of the neurula, it begins to beat synchronously with the host heart and gradually reddens as it initiates blood circulation (E).

A fascinating review on the role of Activin in organ induction. Isn't it wild that in Xenopus embryos, a piece of the animal cap can be induced with Activin at different concentrations and buffers to form the ❤️, kidney, the pancreas, head, tail, and even a whole embryoid 🤯:
doi.org/10.1016/j.cd...

This developing quail embryo looks like it's thinking fiery thoughts for #FluorescenceFriday 🐣🔥🧪. Imaged by the fantastic @vanderspuy.bsky.social

Illustration of sword-tailed newt

Illustration of sword-tailed newt #art #wildlife #nature

Illustration of a toucan (Ramphastos Inca) perched on a tree branch with green and brown leaves. The bird features a large, prominently curved yellow and black beak, blue skin around its eyes, a white throat, a red band across its chest, and predominantly black plumage with red and yellow accents near its tail. The background shows a faint, misty forest scene. The style reflects a detailed 19th-century natural history illustration.

🦜 A monograph of the Ramphastidae, or family of toucans
London: Published by the author, 20, Broad Street, Golden Square, [1852]-1854.

[Source]

🚨 The deadline has been extended until January 31st!🚨