Studies on the p]n(loorine (Hands 



263 



There is no appreciable ditterence in the (|uantity of the granules 

 as a result of twenty-ff>ur hours' fastiiifj. 



A few small ahfolar cells are stained h()iiK)^f»'neously yellow by 

 the orant;e (J of the Mallear}' stain ; indeed, the imclei are coloured blue. 

 There is rarely or never evidence of karyokinesis in any cell of the 

 normal pancreas. I have never been able to cletect a mitosis, even 

 in the pancreas of animals which are still tjrowintj. Occasionally 

 vacuoles occur in some of the cells of the alveoli, but they are never 

 .so large and conspicuous as the cliaracteristic vacuoles which make 

 their appearance as the result of feeding with thyroid (see p. 267). 



Fig. 6. — Section of pancreas of pregnant female rat. Microphotograph ; magnified 

 140 diameters, ibiliory's stain. 



It will be noticed that there is a general diminution of zymogen granules 

 (compare witli fig. 4). An islet is jiresent in tlie middle of the section ; the 

 diminution of the zymogen granules extends also to the alveoli round tliis, which 

 under ordinary conditions are very full of zymogen. 



The connective ti.ssue of the gland is coloured an intense blue by 

 Mallorv. It surrounds the alveoli and lies between the islets and 

 the alveoli. 



The centro-acinar cells are spindle-shaped, with small nuclei 

 exhibiting a faintly granular chromatin. The size of these nuclei 

 is from 2/x to 2-oiu. in Mallory-stained sections there is sometimes 

 seen within the ducts a red material coloured homogeneously — no 

 doubt a coao^ulum from the secretion. 



The islets form a compact mass of cells with irregular sinus-like 

 capillaries between them. The cells of the islets are of nearly equal 

 size. They contain scattered granules much finer than the zymogen 

 granules of the alveolar cells, and staining red by Mallory and Muir. 

 The nuclei are stained faintly blue by Mallory. They are fairly 

 uniform in size, measuring about 5^t. 



