How cell division helps build the body’s left-right organizer

Your heart sits on the left and your liver on the right because of a small structure that forms in the early embryo: the left-right organizer. In zebrafish it’s called Kupffer’s vesicle, and it forms from a cluster of cells called dorsal forerunner cells (DFCs).

In our new paper in Journal of Cell Science, we show that cell division does more than add cells. The earliest DFC divisions help reorganize the cytoskeleton so the organ can take shape.

What we found:

• DFCs first attach to the overlying enveloping layer, and these attachments form without cell division.

• Early divisions are needed to move that organization inward. Cytokinetic bridges, the thin connections between newly divided cells, recruit actin and mark where multicellular “rosettes” form.

• When we blocked early divisions, rosettes failed to form properly and the vesicle stayed close to, or attached to, the enveloping layer. Blocking later divisions had little effect.

• Using laser ablation and live imaging, we saw that disrupting the microtubule bundles at the bridge reduced local actin accumulation.

Our work suggests that when a division happens during development can matter as much as whether it happens.

Read the open-access paper: doi.org/10.1242/jcs.264896
This work was supported by the National Institute of General Medical Sciences (NIGMS).

As Kupffer’s vesicle forms (6 to 12 hpf), dorsal forerunner cells (gray) detach from the overlying enveloping layer (green) while ZO-1 (magenta) shifts from the contact surface to internal junctions.

Hehnly Lab Highlight: Favour Ononiwu Interview on Recent Study

We are excited to share a first-person interview featuring Hehnly Lab PhD graduate Favour Ononiwu, discussing her recent work on the zebrafish left–right organizer. Her study provides new structural insights into centrosomes and cilia using volume electron microscopy, advancing our understanding of how cellular architecture supports developmental patterning.

Hear directly from Favour about the scientific motivation, experimental approaches, and key findings behind this work:
👉 Read the interview

New Preprint: Cytoskeletal Remodeling and Junction Dynamics During KV Morphogenesis

We are pleased to share our latest preprint, now available on BioRxiv:
Read the Preprint

Understanding how epithelial architecture emerges de novo during development remains a central question in cell and developmental biology, particularly in systems where polarity and junctional organization must be established without a pre-existing template. The zebrafish left–right organizer provides a tractable in vivo context to define how transient cell–cell interactions are coordinated with cytoskeletal remodeling to drive tissue morphogenesis.

Our recent study, now available on bioRxiv, examines how dorsal forerunner cells (DFCs) dynamically remodel junctional architecture during Kupffer’s vesicle morphogenesis. Led by postdoctoral researcher Yan Wu, graduate student Yiling Lan, and exceptional undergraduate researchers Athena Allred and Carys Timpson, the work combines high-resolution imaging with quantitative analyses to show that ZO-1–based junctional assemblies form at DFC–EVL interfaces and are progressively reorganized as DFCs transition into a cohesive epithelial cyst. In parallel, we identify a role for early mitotic events and cytokinetic bridge–derived microtubule bundles in organizing actin enrichment and nucleating rosette-like structures, linking cell division to the emergence of epithelial architecture during left–right organizer development.

New Preprint: Structural Diversity and Essential Functions of Zebrafish Left-Right Organizer Cilia

We are excited to share our new preprint on bioRxiv, Functionally Essential and Structurally Diverse: Insights into the Zebrafish Left-Right Organizer’s Cilia via Optogenetic IFT88 Perturbation and Volume Electron Microscopy . This work was led by Favour Ononiwu (Hehnly lab Graduate student) with contributions from Melissa Mikolaj (NCI- Narayan Lab), Christopher Dell (NCI-Narayan Lab), Abdalla Wael Shamil (Hehnly lab undergraduate), Kedar Narayan (NCI), and Heidi Hehnly.

Why this study matters

During vertebrate embryogenesis, the left-right organizer (LRO) generates asymmetric fluid flow that initiates left-right body patterning. In zebrafish, this role is carried out by a transient epithelial organ known as Kupffer’s Vesicle (KV). The cilia within KV have long been known to generate flow, but their structural heterogeneity and contribution to KV morphogenesis have remained unclear.

Our approach

We combined two powerful tools:

• Optogenetics: Using a newly engineered sox17:Cry2-GFP zebrafish line, we clustered the intraflagellar transport protein IFT88 in KV progenitors via blue-light activation. This perturbation impaired ciliogenesis and disrupted lumen formation, establishing a direct role for cilia in KV morphogenesis.

• Volume electron microscopy (vEM): We generated the first high-resolution 3D ultrastructural map of a mature KV, enabling unprecedented analysis of ciliary architecture across the tissue.

Key findings

• Only ~70% of cilia retained both mother and daughter centrioles, suggesting that centriole elimination may occur during KV development.

• Among centrioles, distal appendages (34%), subdistal appendages (92%), and rootlet fibers (5%) were present in highly variable patterns, revealing remarkable structural diversity.

• Cilia were frequently associated with membrane-bound vesicles, including ciliary-associated vesicles (CaVs) and dense vesicles (CaDVs), with distinct spatial distributions across the KV.

Broader implications

Our findings uncover previously unrecognized complexity in LRO organization. The structural specialization of KV cilia suggests that they may contribute not only to generating flow but also to organizing the architecture of the organ itself. This work adds to a growing appreciation that cilia are not uniform organelles, but instead exhibit context-specific diversity that underpins their function.

Next steps

We anticipate that these insights will inform broader studies of ciliary specialization across tissues and their role in developmental disorders linked to left-right asymmetry.

👉 Read the full preprint here.