whole-mount-immunostaining-of-fetal-and-neonatal-mouse-ovaries

Whole Mount Immunostaining of Fetal and Neonatal Mouse Ovaries

The ovarian reserve consists of the oocytes available to a female for reproduction and are found in primordial follicles, each containing one oocyte ...

Syracuse University

Cellular proliferation is vital for tissue development, including the Left-Right Organizer (LRO), a transient organ critical for establishing the vertebrate LR body plan. This study investigates cell redistribution and the role of specific progenitor cells in LRO formation, focusing on cell lineage and behavior. Using zebrafish as a model, we mapped all mitotic events in Kupffer's Vesicle (KV), revealing an FGF-dependent, anteriorly enriched mitotic pattern. With a KV-specific fluorescent microtubule (MT) line, we observed that mitotic spindles align along the KV's longest axis until the rosette stage, spindles that form after spin, and are excluded from KV. Early aligned spindles assemble cytokinetic bridges that point MT bundles toward a tight junction where a rosette will initially form. Post-abscission, repurposed MT bundles remain targeted at the rosette center, facilitating actin recruitment. Additional cells, both cytokinetic and non-cytokinetic, are incorporated into the rosette, repurposing or assembling MT bundles before actin recruitment. These findings show that initial divisions are crucial for rosette assembly, MT patterning, and actin remodeling during KV development.

Specific Mitotic Events Drive Cytoskeletal Remodeling Required for Left-Right Organizer Development.

Cell proliferation is crucial for tissue development. Here, we investigate its role in the left-right organizer, which establishes the left-right axis. In zebrafish, we mapped mitotic events in Kupffer's vesicle (KV) and identified an anteriorly enriched, FGF-dependent mitotic pattern. Laser ablation of mitotic cells and pericentrin-null mutants, both reducing mitotic events, resulted in smaller lumens, confirming that cell division is essential for KV development. Pericentrin-null mutants also exhibited defects in leftward cardiac jogging, indicative of KV dysfunction. Using a KV-specific fluorescent microtubule marker, we found that the KV rosette is a transient, centrally organized cluster interconnected by cytokinetic bridges and containing microtubule bundles. This structure emerges after the first four divisions and precedes lumen formation. Mitotic events during KV rounding coincide with rosette formation, spindle rotation and cell extrusion, likely driven by increased packing. Eliminating the first four mitotic events disrupted rosette formation and prevented normal KV rounding. These findings demonstrate that mitotic events are crucial for KV development, with cell division timing shaping KV architecture and function.

Article	Year
Specific Mitotic Events Drive Cytoskeletal Remodeling Required for Left-Right Organizer Development. bioRxiv : the preprint server for biology\| PubMed ID: 38798489	2024
Specific mitotic events drive left-right organizer development. Development (Cambridge, England)\| PubMed ID: 40230260	2025

Kirsten Rasmussen

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