On the basis of our model of phototactic movements of the multicellular alga V. rousseletii, and taking into account previous considerations by Hoops [ 29] and Kirk [ 6], we conclude that the following evolutionary innovations were required to allow for phototactic movements after the transition from a unicellular Chlamydomonas-like ancestor to the multicellular V. rousseletii: 1.
Then, we introduced two order parameters to measure the directional and cohesive cell movement, which characterize the collectivity of multicellular movement: (1) the degree of forward movement and (2) the spatial correlation length.
A mathematical model for cell movement in multicellular systems has been developed that allows us to simulate and visualize, in three dimensions, individual cell movements in a number of multicellular systems.
Indeed, in response to the increase in cell cell adhesion strength in the model, the movement distance of the forward edge became long, and the two order quantities for the collectivity of multicellular movement also increased as the experimental data show (Fig. 5E G).
Three quantities for the quantification of multicellular movement were introduced.
We consider that the detailed analysis of molecular and mechanical factors about cell migration leads to a better understanding of multicellular movement.
Although there appears to be a positive correlation between the collectivity of multicellular movement and the strength of intercellular adhesion, it is unclear whether or not intercellular adhesion is a sufficient factor for generating collective cell movement.
Melanoma cells have been indicated to move in cohorts of multicellular clusters but the contextual inhibition of β1 integrins abolished these collective movement, thereby inducing detachment of individual single moving cells using amoeboid style to invade, i.e a collective to amoeboid transition (CAT) [ 91].
Then, what controls such different multicellular movements of epithelial tissue?
32 Later, organizing tips become the sources of cAMP waves (Fig. 1), which direct the movement of cells in multicellular structures.
