Dating groups yolk
However, direct evidence supporting this model was lacking.
Joined forces: lab experiments and physical theory To understand the physical basis of this segregation process, Shayan Shamipour, Ph D student in the research group of developmental biologist Carl-Philipp Heisenberg, teamed up with the research group of theoretical physicist Edouard Hannezo.
Instead, they discovered that combined pulling and pushing forces within the embryo facilitate the segregation of cytoplasm from the yolk granules.Within these two hours, the cytoplasm, which will later form the animal body, must separate completely from the yolk, which the larva is going to feed on.Previously, cell biologists had proposed that local expansion of the cell surface at one pole of the egg mediates this segregation.Importantly, the theory developed to describe this process can be applied to any segregation due to the forces exerted from an active fluid and could thus also be used to examine potential similar processes in mammalian/human embryos.Size matters But how are these concerted pulling and pushing movements generated?
Instead, they are actively pushed, or rather squeezed, towards the opposite vegetal pole of the egg by comet-like actin structures -- particular actin structures whose function had not been reported in developmental processes before.