Figure 2
From: Synergistic activity of polarised osteoblasts inside condensations cause their differentiation
Confluence, migration and aggregation.
The figure shows a series of frames capturing proliferation of the progenitor mesenchymal cells until confluence (a) and the migration of pre-osteoblasts to the site of skeletogenesis (b). The largely vacant area begins with five cells that continue to proliferate and fill the entire space. Cells until this time only form a monolayer. They can neither migrate nor grow in the third dimension. The centre of the virtual Petri dish serves as the site of skeletogenesis. Only cells that have acquired a pre-osteoblastic phenotype (orange), unlike the initial fibroblast-like cells (blue), migrate towards the centre. The direction of one of these pre-osteoblasts has been indicated using the red arrow-head. (c) displays progression in terms of cellular aggregation. Aggregation can be easily visualised in the final two frames of (c), which show a ventral view of the monolayer after the pre-osteoblastic cells have triggered condensation initiation at the top. As the frames move towards right, time increases by 6.25 days in (a), 30 hours in (b) and 45 hours in (c).
