One of the earliest signs of gastrulation in reptiles, birds and mammals (amniotes) is the appearance of a thickening at the midline of the developing embryo, the primitive streak. Here ...
1). Joubin and Stern conclude that, during the primitive-streak stages of gastrulation, rather than there being a resident node cell population most cells in fact enter and leave the node quite ...
This signaling is crucial for cell differentiation and the extension of the primitive streak. This structure eventually forms ...