154 



PRACTICAL MICROSCOPY. 



surfaces. Examples are found in the uterus, stomach, small in- 

 testine, etc. 



COILED TUBULAR GLANDS. 



Tubular glands are often greatly elongated, with the blind ex- 

 tremity coiled. This variation presents the simplest differentiation 

 between the part of the tube which is secretory, and the duct, or 

 drainage part. With this change in function of the different ex- 

 tremities of the tube will occur a change of epithelium. The cells 

 belonging to the duct-end will usually retain the columnar form; 

 while the actively secreting elements will become enlarged, more 

 nearly filling the tube, and assume a polyhedral form from pressure. 



FIG. 103. DIAGRAM. COILED TUBULAR GLAND. 

 Same references as Fig. 102. 



Examples have already been seen in the sweat tubes of the skin 

 sudoriferous glands and the mucous glands of the submucosa of the 

 larger bronchi. 



BRANCHED TUBULAR GLANDS. 



With the branching of the duct portion of gland tubules, there usu- 

 ally occurs a dilatation of the extremities into alveoli, although pure 

 examples of branched tubular glands are afforded in the gastric and in- 

 testinal glands, those of the cervix uteri, etc. 



The most nearly typical branching of gland-like tubules is afforded 

 by the tubuli uriniferi of the kidney although not contained in a 



