Tension-dependent collective cell movements in the early gastrula ectoderm of Xenopus laevis embryos |
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Authors: | L V Beloussov N N Louchinskaia A A Stein |
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Institution: | (1) Department of Embryology, Faculty of Biology, Moscow State University Moscow 119899 Russia E-mail: lbelous@soil.msu.ru Tel.: +7-95-9393915, Fax: +7-95-9394309, RU;(2) Institute of Mechanics, Moscow State University, Moscow 119899 Russia, RU |
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Abstract: | Ventral ectodermal explants taken from early gastrula embryos of Xenopus laevis were artificially stretched either by two opposite concentrated forces or by a distributed force applied to the internal
explant’s layer. These modes of stretching reflect different mechanical situations taking place in the normal development.
Two main types of kinematic response to the applied tensions were detected. First, by 15 min after the onset of concentrated
stretching a substantial proportion of the explant’s cells exhibited a concerted movement towards the closest point of the
applied stretching force. We define this movement as tensotaxis. Later, under both concentrated and distributed stretching,
most of the cell’s trajectories became reoriented perpendicular to the stretching force, and the cells started to intercalate
between each other, both horizontally and vertically. This was accompanied by extensive elongation of the outer ectodermal
cells and reconstruction of cell-cell contacts. The intercalation movements led first to a considerable reduction in the stretch-induced
tensions and then to the formation of peculiar bipolar ”embryoid” shapes. The type and intensity of the morphomechanical responses
did not depend upon the orientation of a stretching force in relation to the embryonic axes. We discuss the interactions of
the passive and active components in tension-dependent cell movements and their relations to normal morphogenetic events.
Received: 26 April 1999 / Accepted: 30 August 1999 |
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Keywords: | Morphogenetic movements Mechanical stresses Cell intercalation Xenopus laevis |
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