386 



EXPERIMENTAL FISH EMBRYOLOGY 



^ 



IIW 



a 



VITAL-STAINING OF THE AREAS 



OF THE PRESUMPTIVE NERVOUS 



SYSTEM OF FUNDULUS 



VITAL-STAINING OF THE 



AREAS OF THE PRESUMPTIVE 

 MESODERM OF FUNDULUS 



Drawings A to D represent stages in the development 

 of a single embryo, reading from left to right. 



Note that the mesoderm is derived from the lateral 

 wings of the embryonic shield, from the germ ring, 

 from the germ ring 180° distant from the embryonic 

 axis, and from the extra -embryonic membrane. 



A, B, C, represent stages in the early development 



of a single embryo. 



First embryo - entire nervous area. 



Second embryo - spinal cord area. 



Third embryo - mid- and hind-brain areas. 



Fourth embryo - nervous contributions from either 



side of the embryonic axis. 

 Fifth embryo - fore-brain and eyes from materia) 



anterior to the shield. 



It 



I 



(From Oppenheimer 1936: Jour. Exp. Zool. 73:405) 



Successive stages in the development of embryos in which the presumptive 

 endodcrm has been vitally stained. When stain has been applied to the 

 posterior lip of the early embryonic shield (A), the invagination of stained 

 cells may be watched as gastralation proceeds (B). Occasionally the stain 

 still remains localized in the region of Kupffer's vesicle after the blastopore 

 is closed (C). 



