Bidirectional redistribution of actomyosin drives epithelial invagination in ascidian siphon tube morphogenesis.

Bidirectional actomyosin redistribution drives epithelial invagination, with 2 distinct phases involving apical constriction and lateral contractility in ascidian siphon tube development.

• Why it matters: Understanding the mechanical mechanisms of tissue morphogenesis is crucial for insights into organ formation and developmental biology, yet the precise actomyosin dynamics remain unclear.
• What they did: The study used live imaging, genetic mutants, optogenetics, and vertex model simulations to analyze actomyosin reorganization during two invagination stages in Ciona siphon tube morphogenesis, focusing on actomyosin redistribution between apical and lateral regions.
• The result: Findings demonstrate that bidirectional actomyosin redistribution orchestrates invagination by first promoting apical constriction and later lateral contractility, revealing a mechanical model that advances understanding of epithelial morphogenesis.