VITELLINE MEMBRANE 



FOLLICLE LAYER 



Fig. 94. Vitelline membrane of an almost mature egg of the frog. 



YOLK 



FOLLICULAR 

 E PITH ELI U M 



PRO LON GAT IONS OF 

 FOLLICULAR CELL 



OUTER 

 LAYE R 

 INNER 



LAYER 

 K NO B-Ll KE 



ENLARGEMENTS 

 OF FOLLICULAR 

 P ROLONGATIONS 



FUNDAMEN TAL 

 SUBSTANCE 



Fig. 95. Zona radiata (zona pellucida) or vitelline membrane of Chrysemys picta. 



(After Thing, '18.) 



FOL LI CLE C ELLS 



ZONA R ADI ATA 



Fig. 96. Zona radiata of the egg of the fowl. (After Brambell, '25.) 



166 



