Hypoblast controls mesoderm generation and axial patterning in the gastrulating rabbit embryo

Area of Science:

• Developmental biology
• Mammalian embryogenesis
• Gastrulation

Background:

• Gastrulation involves epiblast cells undergoing epithelial-to-mesenchymal transition to form mesoderm.
• The primitive streak establishes the anterior-posterior axis in vertebrate embryos.
• Hypoblast signals regulate mesoderm induction and anterior-posterior axis formation.

Purpose of the Study:

• To investigate the roles of Cerberus and Dickkopf signaling molecules in rabbit gastrulation.
• To define expression patterns of key molecules in a non-mouse mammal.
• To elucidate the hypoblast's role in establishing the anterior-posterior axis.

Main Methods:

• Analysis of Cerberus and Dickkopf expression in rabbit embryos.
• Loss-of-function experiments involving hypoblast removal.
• Culture system to assess epiblast response and mesoderm formation (Brachyury expression).

Main Results:

• Cerberus and Dickkopf exhibit complementary expression patterns in the hypoblast and primitive streak.
• Epiblast susceptibility to mesoderm induction is stage-dependent and spatially restricted.
• Hypoblast removal disrupts normal mesoderm formation and axis patterning.

Conclusions:

• The anterior-posterior axis in mammalian embryos is initially patterned by hypoblast signals.
• Hypoblast-derived signals are crucial for fixing the axis through primitive streak formation.
• This study confirms a conserved mechanism of axis formation in mammals.