332 



MICROSCOPIC ANATOMY OF THE ORGANS. 



penis, and prepuce (Tyson's glands)). They are wanting in 

 the palms of the hands and soles of the feet. 



They are simple or branched alveolar single glands, club- 

 like or pyriform. Their size varies from 0.2 mm. to 2.2 mm. 



FIG. 254. 



Outer root 

 'sheath 



Duct 



Hair root 





Sebaceous gland from the human scalp. X 120. 



in length. The largest are found often associated with small, 

 thin hairs, such as those in the nose. Their ducts open into 

 the upper third of the hair follicle. 



Sebaceous glands are surrounded by a connective-tissue 

 capsule which originates in the hair follicle or in the corium 

 itself. The glands consist of epithelial cells which come from 

 the outer root sheath ; or, if the gland is not in connection 

 with a hair, from the epidermis of the skin. The epithelial 

 cells forming the neck of the gland retain unchanged the 

 characteristics of the cells from which they arise. In the 

 body of the gland, however, they are modified somewhat by 



