Planar Cell Movements and Axial Patterning During Early Gastrulation of the Rabbit Embryo

by Viktoria Stankova
Cumulative thesis
Date of Examination:2014-01-21
Date of issue:2014-05-22
Advisor:Prof. Dr. Christoph Viebahn
Referee:Prof. Dr. Ernst A. Wimmer
Referee:Prof. Dr. Tomas Pieler
Persistent Address: http://dx.doi.org/10.53846/goediss-4463

 

 

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Abstract

English

During mammalian gastrulation cellular mechanisms such as cell movements and cell proliferation give rise to the primitive streak and thereby fix the body axes and create the basis for the ‘milieu intérieur’. Although many aspects of cellular and molecular processes controlling gastrulation are well described in a variety of vertebrate species, the spatio-temporal cellular behaviour during mammalian gastrulation is still poorly understood, particularly in mammals with a flat embryonic disc. Using the rabbit blastocyst with its late implantation and mammotypical flat embryonic disc this doctoral thesis presents: (1) live imaging of the emerging primitive streak which is formed by so-called L- and U-turns of individual cells, intercalation-like ‘processional cell movements’ and oriented cell divisions and (2) evidence – obtained by chemical inhibition of Rho kinase (ROCK) – of the importance of the Wnt-planar cell polarity (PCP) pathway for cell movements during the primitive streak formation but not for the formation of mesoderm and of the dorsal organizer. In addition, ROCK inhibition in the rabbit blastocyst leads to ancestral gastrulation forms in a dose-dependent manner, which may represent the evolutionary pathway of vertebrate gastrulation. Thus, the rabbit with its ‘prototypical’ mammalian gastrulation form may become a key model organism for understanding the mechanisms controlling early mammalian development as well as the evolution of embryonic development.
Keywords: mammalian gastrulation; axis differentiation; cell migration; primitive streak
 
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