Figure 11.10. Cell movements of the primitive streak of the chick embryo.

Figure 11.10

Cell movements of the primitive streak of the chick embryo. (A-C) Dorsal view of the formation and elongation of the primitive streak. The blastoderm is seen at (A) 3–4 hours, (B) 7–8 hours, and (C) 15–16 hours after fertilization. The early movements of the migrating epiblast cells are shown by arrows. (D-F) Formation of notochord and mesodermal somites as the primitive streak regresses, shown at (F) 19–22 hours, (E) 23–24 hours, and (F) the four-somite stage. Fate maps of the chick epiblast are shown for two stages, the definitive primitive streak stage (C) and neurulation (F). The endoderm has already ingressed beneath the epiblast, and convergent extension is seen in the midline. (Adapted from several sources, especially Spratt 1946 and Smith and Schoenwolf 1998.)

From: Early Development in Birds

Cover of Developmental Biology
Developmental Biology. 6th edition.
Gilbert SF.
Sunderland (MA): Sinauer Associates; 2000.
Copyright © 2000, Sinauer Associates.

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