132 



TWELFTH LECTURE. 



We shall, therefore, comprehend that those cells, flattened 

 into the thinnest plates, such as we previously met with in the 

 pavement epithelium, are absent. 



The gland cell is a membraneless, cubical thing, occasion- 

 ally somewhat flattened from above downwards, in other 

 cases rendered cylindrical by lateral compression. The for- 

 mer shape is represented by the cells of the liver, with a size 

 of 0.018 to 0.226 mm. (Fig. 121). The cells (Fig. 122, b) of the 

 " gastric mucous glands " of the dog are taller and more slen- 

 der. The elements of the Lieberkiihnian 

 glandular tubes of the small intestine have 

 likewise assumed the cylindrical form, as our 

 Fig. 117, b (representing a longitudinal sec- 

 tion of this tube) teaches. 



Gland cells covered with ciliae are verv 

 rarely met with in man. They are only 

 known in the uterine tubes. 



Many gland cells — we here allude chiefly 

 to those of the liver and kidney — appear 

 to constitute tolerably permanent structures. 

 In others the cellular elements retain the 

 great perishability of the epithelium, and 

 perish in the formation of the secretion. 



Let us take, for example, a sebaceous 

 gland of the external integument, a small 

 clustered structure. An acinus is shown in 

 Fig. 123, A. 



It is covered by several cell layers. In 

 the cavity (/;) we meet with a fatty mass, 

 which subsequently becomes free as sebum 

 cutaneum. 



How has the latter been formed ? 

 In the peripherical cells, those lying im- 

 mediately against the wall of the gland 

 vesicle, one already notices an increasing deposit of fat 

 molecules. This is, therefore, the fatty degeneration which 

 we have already mentioned at page 13. It causes the 



Fie;. 121. — Human 

 liver cells. 



Fig. 122. — From a gas- 

 tric mucous gland of the 

 dog ; a, lower portion of 

 the excretory duct ; />, 

 commencement of the 

 glandular canal. 



