FIG. 5. Parts of three cells from the sporogenous tissue of the African violet 

 (Saint paulia ionantha) . A nucleus (N) with a prominent nucleolus (nu) is shown 

 at the upper left. Dense primary walls (cu) separate the cells and transect the 

 image. The endoplasmic reticulum of these cells is made up characteristically of 

 lamellar and vesicular elements. These are not organized into obvious patterns as 

 in the case of the preceding cells, but seem instead to be more or less randomly 

 distributed. Ribosomes are attached preferentially to the lamellar cisterna, but as 

 is typical of undifferentiated and rapidly proliferating cells, the majority of the 

 ribosomes (ri) are free in the cytoplasmic matrix. Mitochondria are indicated at 

 m, and smooth ER at ser. Here we encounter a morphology that is quite typical of 

 embryonic or meristematic cells: an abundance of free ribosomes and a sparse ER 

 without obvious organization. (Courtesy of Myron C. Ledbetter.) Magnification: 

 35,000 X. 



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