SIMPLE EPITHELIUM 



orifice of the stomach to the anus, and b, wholly or in part all the ducts of the 

 glands opening on its free surface, and c, many gland ducts in other regions 

 of the body, e.g., mammary, salivary, etc. The intracellular and intra- 

 nuclear networks are well developed, and in some cases the spongioplasm is 



FIG. 23. Simple Columnar Epithelial Cells from the Human Intestinal Mucous 

 Membrane, a, Mucous (goblet) cell; b, basement membrane; c, cuticle; d, leucocyte 

 nucleus; e, germinating cell. (Bailey.) 



arranged in rods or longitudinal striae at one part of the cell, as in the cells of 

 the ducts of salivary glands. The protoplasm of columnar cells may be 

 vacuolated and may also contain fat or other substances seen in the form of 

 granules. Certain columnar cells transform a large part of their protoplasm 

 into mucin, goblet cells, figure 24, which is discharged by the open mouth 



FIG. 



FIG. 



FIG. 24. Goblet Cells. (Klein.) 



FIG. 25. Cross-section of a Villus of the Intestine, e, Columnar epithelium with 

 striated border; g, goblet cell, with its mucus partly extruded; I, lymph corpuscles between 

 the epithelial cells; b, basement membrane; c, sections of blood capillaries; m, section of 

 plain muscle fibers; c I, central lacteal. (Schafer.) 



of the goblet, leaving only a nucleus surrounded by the remains of the proto- 

 plasm in its narrow stem. This transformation is a normal process which 

 is continually going on during life, the cells themselves being supposed to 

 regenerate into their original shape. 



