9 



Gastrulation 



A. Some definitions and concepts 



1. Gastrulation 



2. Primitive vertebrate body plan in relation to the process of gastrulation 



a. Fundamental body plan of the vertebrate animal 



b. The gastrula in relation to the primitive body plan 



c. Chart of blastula, gastrula, and primitive, body-form relationships (fig. 188) 



B. General processes involved in gastrulation 



C. Morphogenetic movement of cells 



1. Importance of cell movements during development and in gastrulation 



2. Types of cell movement during gastrulation 



a. Epiboly 



b. Emboly 



3. Description of the processes concerned with epiboly 



4. Description of the processes involved in emboly 



a. Involution and convergence 



b. Invagination 



c. Concrescence 



d. Cell proliferation 



e. Polyinvagination 



f. Ingression 



g. Delamination 

 h. Divergence 



i. Extension 



D. The organization center and its relation to the gastrulative process 



1. The organization center and the primary organizer 



2. Divisions of the primary organizer 



E. Chemodifferentiation and the gastrulative process 



F. Gastrulation in various Chordata 

 1. Amphioxus 



a. Orientation 



b. Gastrulative movements 



1) Emboly 



2) Epiboly 



3) Antero-posterior extension of the gastrula and dorsal convergence of the 

 mesodermal cells 



4) Closure of the blastopore 



c. Resume of cell movements and processes involved in gastrulation of Amphioxus 



1) Emboly 



2) Epiboly 



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