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TEXT-BOOK OF EMBRYOLOGY. 



Endoplasm with 

 "white" fibers 



Ground 

 substance 



Ectoplasm 



Elastic fibers 



FIG. 150. Connective tissue cells from intervertebral disk of calf embryo; showing origin of 

 "white" and elastic fibers in protoplasm of cells. Ectoplasm represents a modified part 

 of the protoplasm (endoplasm). Hansen. 



FIG. 151. Vertical section through frontal bone of human foetus of 4 months. 

 (Intramembranous ossification.) Photograph. 



