Mechanical analysis of chorion softening in prehatching stages of zebrafish embryos

Deok Ho Kim, Chang Nam Hwang, Yu Sun, Sang Ho Lee, Byungkyu Kim, Bradley J. Nelson

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


During early development, the chorion envelope of the zebrafish embryo undergoes a thinning process called "chorion softening," which has so far only been characterized chemically. In this study, a micromechanical force sensing system was used to characterize and quantitate mechanical modifications of the zebrafish embryo chorion during early development. Quantitative relationships between applied forces and chorion structural deformations were established at various embryonic stages. The measured penetration force into the chorion at the blastula stage was 1.3-fold greater than those at the prehatching stage. Furthermore, chorion elastic modulus values were determined by using a biomembrane elastic model. The elastic modulus of the chorion at the blastula stage was 1.66-fold greater than that at the prehatching stage, thus indicating that the chorion envelope become mechanically "softened" at the prehatching stage. The experimental results quantitatively describe "chorion softening," which is most likely due to proteolytic activities at the prehatching stage. Gradual chorion softening during embryonic development was also artificially achieved by treating blastula chorion with pronase, a proteolytic enzyme. The forces required to penetrate the promise-treated chorion were similar to those at the prehatching stage. This similarity suggests that "chorion softening" may be induced by the release of protease from the embryos, and the chemical nature of the process involves proteolytic fragmentation of the ZP2 protein.

Original languageEnglish
Article number1637449
Pages (from-to)89-94
Number of pages6
JournalIEEE Transactions on Nanobioscience
Issue number2
Publication statusPublished - 2006 Jun


  • Cellular force sensing
  • Chorion softening
  • Elastic modulus
  • Hatching
  • Peptide fragmentation
  • Protease
  • Proteolytic activities
  • Zebrafish embryo

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Medicine (miscellaneous)
  • Biomedical Engineering
  • Pharmaceutical Science
  • Computer Science Applications
  • Electrical and Electronic Engineering


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