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Fig. 2. Fibrils elaborated under the mesendoderm and at the limit of involution. A: The blastocoele roof (bcr) of the animal cap ectoderm
with accompanying mesendodermal mantle (mese) is dissected from whole fixed embryos. B: A series of confocal sections were
collected and projected into a single image and show dense fibrils in the center of the roof (bcr) surrounded by a ring of lower density
matrix underneath the migrating mesendoderm (mese; arrows show direction of mesendoderm migration in B and D). C: High
magnification of the inset in B shows that the density difference is due to gaps (asterisks) in the matrix behind the leading edge cells of
the mesendoderm (indicated by the dashed line). D: A cross-section through the confocal stack (along the solid line in C) shows gaps
in the matrix (asterisks) immediately behind the migratory leading edge of the cell (arrowhead; arrow shows direction of migration).
E: Confocal from tissue samples cut from a lateral region of the a fixed embryo were collected in en face orientation. F: The resulting
confocal series are projected to a single plane and show the abrupt edge of fibronectin fibrils near the blastopore lip (arrowheads). Scale
of C and D are the same. ar, archenteron; bp, blastopore; bc, blastocoele; no, notochord. |
