Study under high power. The cells of the upper 

 layer (free border) are large flat scales with a smooth free 

 edge. The lower border is often slightly pitted, these 

 depressions receiving the cells of the next lower layer. 

 These large-cells have one or two nuclei. The cells of the 

 second layer are pear-shaped or irregularly columnar. The 

 cells of the deeper layer are triangular or spindle-shaped, 

 and fit in between the cells of the second layer. Sketch a 

 portion of the epithelium. 



DRAWINGS FOR LESSON IV. 



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