GASTRULATION 389 



2. Gastrulation in Amphibia with particular reference to the frog 



a. Introduction 



1 ) Orientation 



2) Physiological changes which occur in the presumptive, organ-forming areas 

 of the late blastula and early gastrula as gastrulation progresses 



b. Gastrulation 



1) Emboly 



2) Epiboly 



3) Embryo produced by the gastrulative processes 



4) Position occupied by the pre-chordal plate material 



c. Closure of the blastopore and formation of the neurenteric canal 



d. Summary of morphogenetic movements of cells during gastrulation in the frog 

 and other Amphibia 



1) Emboly 



2) Epiboly 



3. Gastrulation in reptiles 



a. Orientation 



b. Gastrulation 



4. Gastrulation in the chick 



a. Orientation 



b. Gastrulative changes 



1 ) Development of primitive streak as viewed from the surface of stained 

 blastoderms 



2) Cell movements in the epiblast involved in primitive-streak formation as 

 indicated by carbon-particle marking and vital-staining experiments 



3) Cell movements in the hypoblast and the importance of these movements 

 in primitive-streak formation 



4) Primitive pit notochordal canal 



5) Resume of morphogenetic movements of cells during gastrulation in the 

 chick 



5. Gastrulation in mammals 



a. Orientation 



b. Gastrulation in the pig embryo 



c. Gastrulation in other mammals 



6. Gastrulation in teleost and elasmobranch fishes 



a. Orientation 



b. Gastrulation in teleost fishes 



1) Emboly 



2) Epiboly 



3) Summary of the gastrulative processes in teleost fishes 



a) Emboly 



b) Epiboly 



4) Developmental potencies of the germ ring of teleost fishes 



c. Gastrulation in elasmobranch fishes 



7. Intermediate types of gastrulative behavior 



G. The late gastrula as a mosaic of specific, organ-forming territories 

 H. Autonomous theory of gastrulative movements 



I. Exogastrulation 



J. Pre-chordal plate and cephalic projection in various chordates 

 K. Blastoporal and primitive-streak comparisons 



