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sue. The acini of the mucous glands are larger than those 

 of the serous glands. Study the structure of the acini 

 under high power. 



In the mucous glands the acini are surrounded by a 

 membrana propria which is nearly filled with clear mucous 

 cells stained a steel-gra}^. The nuclei are in the peripheral 

 part of the cells. Many of the acini will show a crescent 

 of more deeply stained cells, the demilunes of Heidenhain, 

 lying between the mucous cells and the membrana propria. 

 The ducts are regularly round or oval with relatively large 

 lumina. They are lined by a single layer of columnar 

 cells with striated protoplasm. 



The acini of the serous glands also have a limiting 

 membrana propria. They are lined by cuboidal or 

 polyhedral cells with the nuclei near the center of the 

 cells. They often have a granular protoplasm. The 

 structure of the ducts is the same as in the mucous glands. 



Sketch a duct and a number of acini surrounding it, 

 from both mucous and serous glands as seen under high 

 power. 



(f) Mucous and Serous Salivary Glands Stained 



in Delafield's Haematoxylin. 



Pieces of the submaxillary and parotid glands of a dog were 

 hardened in mercuric, chloride, stained in Delafield's hsematoxylin, 

 and a piece of each gland embedded side by side in a block of 

 paraffin, and sectioned. Fix to the slide and mount in balsam. 



The structure seen in (e) will again be observed. 



(g) Mucous and Serous Salivary Glands Stained 



in Borax Carmine. 



Pieces from the submaxillary and parotid glands of a dog were 

 hardened in absolute alcohol, stained in borax carmine, pieces of 

 each gland embedded as above, and sectioned. Fix and mount. 



The last two preparations are given to the student to 

 show the structure of mucous and serous glands as shown 

 by ruematoxylin and carmine stains to facilitate their 

 recognition in sections to be given later on in the work. 





