Editing Invagination (section)

===''Amphioxus'' gastrulation===
[[File:Invagination.jpg|thumb|Invagination process in an amphioxus|337x337px]]
The invagination in ''[[amphioxus]]'' is the first cell movement of gastrulation. This process was first described by [[Edwin Conklin|Conklin]]. During gastrulation, the [[blastula]] will be transformed by the invagination. The [[endoderm]] folds towards the inner part and thus the [[blastocoel]] transforms into a cup-shaped structure with a double wall. The inner wall is now called the [[archenteron]]; the primitive gut. The archenteron will open to the exterior through the [[blastopore]]. The outer wall will become the [[ectoderm]], later forming the [[epidermis]] and [[nervous system]].<ref>{{cite book |last=Browder |first=Leon |date=1984 |title=Developmental Biology |location=Canada |publisher=CBS College Publishing |page=599 |isbn= 4833702010 }}</ref>