Surface tensions of embryonic tissues predict their mutual envelopment behavior

Area of Science:

• Developmental Biology
• Biophysics
• Cell Biology

Background:

• Embryonic tissues move via liquidlike spreading.
• The differential adhesion hypothesis proposes cell adhesion generates tissue surface tensions guiding these movements.
• This hypothesis is analogous to immiscible liquid spreading, where lower surface tension liquids envelop higher surface tension ones.

Purpose of the Study:

• To physically test the differential adhesion hypothesis.
• To measure the surface tensions (sigmas) of chick embryonic tissues.
• To correlate measured surface tensions with observed tissue spreading and envelopment behaviors.

Main Methods:

• Aggregates of five chick embryonic tissues were formed.
• A parallel plate compression apparatus was used to measure tissue surface tensions.
• Measured surface tensions were compared to the tissues' mutual spreading behaviors.

Main Results:

• Chick embryonic tissue aggregates exhibited elasticoviscous liquid behavior with measurable surface tensions.
• Surface tension values ranged from 1.6 dyne/cm (neural retina) to 20.1 dyne/cm (limb bud mesoderm).
• The measured surface tensions followed the precise sequence predicted by the differential adhesion hypothesis for observed envelopment patterns.

Conclusions:

• The differential adhesion hypothesis is supported by direct physical measurements of tissue surface tension.
• Tissue surface tension is a key factor governing cell-adhesion-driven tissue spreading and arrangement during embryonic development.
• This study provides a quantitative framework for understanding tissue morphogenesis.