Fig. 4. Basal part of a proximal convoluted tubule cell of the mouse kidnej'. The plasma membrane 

 which faces the basement membrane (BM) is highlj^ infolded, but at the point where it turns (arrow) 

 another portion of the cytoplasm is always interposed. The basal cell cytoplasm is thus divided into 

 coarse lamellae which contain mitochondria (M) and abundant RXA particles (R). Magnification 

 32,000X. 



Fig. 5. Basal part of a collecting tubule cell of the mouse kidney. As in the proximal convolution, 

 the basal plasma membrane is infolded, but as a rule, the turning point (arrow) can be seen without anj' 

 interposed cytoplasmic lamella. The cytoplasmic lamellae are here thinner than in the proximal con- 

 volution and not broad enough to house mitochondria (M). Some RNA-granules (R) are located in the 

 lamellae. The basement membrane (BM) is quite thin. Magnification X46,000. 



170 



