GLANDS 



259 



Except for the ducts of certain mucous glands whose epithelial coat 

 resembles that of the mucous membrane to which they are attached, the 

 ducts of this type of secreting gland are 

 lined by columnar cells whose cytoplasm fre- 

 quently presents a rodded appearance at the 

 deeper end of the cell. The acini contain 

 typical serous or mucous, secreting epithe- 

 lium. Occasionally the secreting cells are 

 also found for some distance beyond the 

 acinus in the lining membrane of the small- 

 est ducts. 



The tubules and acini of these glands are 

 invested with a 

 basement mem- 

 brane and a 

 delicate tunica 

 propria. The 

 acini are united 

 by the connec- 

 tive tissue into 

 small 



FIG. 258. RECONSTRUCTION OP 

 A Mucous GLAND FROM THE 

 RESPIRATORY REGION OF THE 

 NASAL MUCOSA OF A CHILD. 



The duct passes directly into 

 secreting alveoli. A typical 

 X 



small tubulo-alveolar gland, 

 which inclose a 2 00. (After Maziarski.) 



central duct of 



the smallest type, the intercalary (or inter- 

 mediate) duct. These acinar groups are 

 again united into the lobules of the gland 

 by fine bands of connective tissue, and 

 broader bands of loose connective tissue ce- 

 ment the many lobules into one glandular 

 mass. .The intercalary ducts by union within 

 the lobule form numerous small intralobular 

 ducts which approach the periphery of the 

 lobule and at its margin open into the inter- 

 lobular ducts; the latter are found in the 

 broader septa of connective tissue between 

 the lobules. The interlobular ducts by union 

 with one another result in progressively 

 larger branches which finally form the 

 main excretory duct of the gland. 



Simple Saccular Glands. Simple saccular glands occur as the 



FIG. 259. RECONSTRUCTION 

 OF AN INTRALOBULAR DUCT 

 DIVIDING INTO ITS TER- 

 MINAL INTERCALARY DUCTS 

 AND ACINI. 



The terminal divisions of a 

 large compound tubulo-aci- 

 nar gland. The model was 

 made from serial sections of 

 the human pancreas. X 344. 

 (After Maziarski.) 



