Figure 5
- ID
- ZDB-FIG-210927-30
- Publication
- Pulgar et al., 2021 - Apical contacts stemming from incomplete delamination guide progenitor cell allocation through a dragging mechanism
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(A) Schematic diagram showing single isolated DFCs transiting the process of delamination far from the main DFC cluster (green). Single isolated DFCs are either transiting delamination and be attached to extra-embryonic tissues (blue cell; attachment shown as a brown dot) or be detached from these tissues after completing delamination (red cell). (B–D) Movement directionality and persistence of single isolated attached and detached DFCs. Tracking plots of single isolated attached (B) and detached (C) DFCs, and the differences in movement persistence (D), obtained from living Tg(sox17::GFP;actb1::mCherry-utrCH) embryos at around 60% epiboly (n = 17 attached DFCs from eight embryos and 20 detached DFCs from eight embryos). *** (p ≤ 0.001). (E) Time series of dorsal views of confocal z-stack maximum projections of a representative living Tg(sox17::GFP;actb1::mCherry-utrCH) embryo starting at 60% of epiboly (extracted from Figure 4—video 3) showing the movement of three DFCs developing as single cells in isolation from the main DFC cluster (see schematic in panel A). The blue cell is attached to the extra-embryonic yolk syncytial layer (YSL) and enveloping layer (EVL) during the entire series. The red cell is detached from these tissues during the entire series. The yellow cell is initially attached to the EVL but at time 68 min completes delamination and detaches from the EVL. Note that after detaching, DFC movement loses persistence and becomes non-directional. Brown arrows show the accumulation of actin at apical attachments. The brown bracket at time 68 min shows the distance between the position of the apical actin accumulation that labelled the recently lost apical attachment and the position of the detached DFC. White arrows show the vegetal movement of the YSL/EVL margin during epiboly. (F) Comparison of the tracks of the movement of the blue attached DFC shown in (E) and the movement of its apical attachment (brown). Scale bar, 50 µm. (G–I) Correlation plots between the movement persistence of DFCs and their apical attachments (G; Pearson’s r = 0.99984; n = 17 attached cells and apical attachments from eight embryos) and between the movement speed of DFCs and their apical attachments (H; Pearson’s r = 0.96085; n = 276 attached cells and apical attachments from eight embryos), and distribution plot of the distance (length) between the apical attachment and body of DFCs (I; n = 276 apical attachments and DFC bodies from eight embryos). (J) Schematic diagram showing the proposed drag-mediated mechanism guiding the motion of attached DFCs. YSL/EVL vegetal spreading is transmitted to delaminating DFCs through apical attachments to guide their vegetal movements. Single isolated DFCs devoid of apical attachments (detached DFCs) are insensible to YSL/EVL dragging and show non-directional movements. Animal is to the top in all image panels. Source data for all plots are provided in Figure 5—source data 1.
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