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Identifier

000454371

Title

Mechanisms of epithelial organization and cell packing during ectoderm formation in the crustacean Parhyale hawaiensis

Alternative Title

Μηχανισμοί επιθηλιακής οργάνωσης και στοίβαξης κυττάρων κατά την δημιουργία του εκτοδέρματος του καρκινοειδούς Parhyale hawaiensis

Author

Καλογερίδη, Μαρία Ε.

Thesis advisor

Παυλόπουλος, Αναστάσιος

Reviewer

Δελιδάκης, Χρήστος
Streichan, Sebastian

Abstract

Epithelial morphogenesis -the process through which epithelial tissues acquire functional architectures- is driven by changes in cell numbers, shapes and packing. Such changes can result from forces generated at the cellular level. The actomyosin contractility is a main source of force that orchestrates the cell behaviors during epithelial morphogenesis. The mechanisms and the dynamic processes that underlie epithelial morphogenesis are under intense investigation in diverse developmental contexts and model organisms. In this Master’s thesis, I combined confocal time-lapse microscopy with quantitative image analysis to investigate the mechanisms that drive the organization and packing of cells in the ectoderm of the crustacean Parhyale hawaiensis, an emerging model organism. During Parhyale ectoderm morphogenesis, the tissue becomes organized into a highly ordered array of rows and columns of cells. This grid-like arrangement emerges from the progressive addition of cell rows from a pool of unorganized cells at its posterior end, together with stereotyped anterior-posterior-oriented cell divisions in each row. I show that during this process, the nascent Parhyale ectoderm transitions from a hexagonal honeycomb-like pattern, which is typical for most epithelia, into a lattice of predominantly 4-sided square and rectangular cells. I then describe the myosin II dynamics at the subcellular and supracellular scale that correlate and presumably mediate the cell shape changes, cell rearrangements and cell sorting events that occur during Parhyale ectoderm morphogenesis. Finally, I demonstrate the first use of laser ablations in Parhyale embryos that will be a valuable tool to probe the mechanical properties of cells and tissues in vivo. This work sets the stage for future functional studies that will combine imaging of developing embryos with genetic, drug and mechanical perturbations to connect the biochemical with the biophysical basis of epithelial tissue morphogenesis

Language

English

Subject

Actin

Cell rearrangement

Cell shape

Confocal microscopy

Embryonic development

Epithelial morphogenesis

Image analysis

Myosin

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