FIG. 10. Parts of two erythroblasts found in the embryonic liver of the rat. Nuclei 

 are shown at TV, - the image of the one at the lower left includes a distinct envelope 

 (ne). It is characteristic of these cells to show very few elements of the ER. The 

 cytoplasmic matrix, on the other hand, is dominated by large numbers of ribosomes 

 and between these an accumulation of material, probably hemoglobin, of lower 

 density. As differentiation proceeds the ribosomes diminish in number, the reticu- 

 lum disappears, and the matrix becomes uniformly gray. The nuclei are ejected. 

 In this instance a nonfibrous component comes to dominate the cytoplasmic matrix 

 as differentiation proceeds and the ribosomes and ER disappear. Mitochondria are 

 indicated at M, the Golgi component at G, and centrioles at C. (Courtesy of Win- 

 centy Kilarski.) Magnification: 20,000 X. 



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