. Quain's elements of anatomy . ation of a duct in the tubularalveoli, a : the two zones in the alveolarcells are well seen. The secreting cells of the pan-creas have a very characteristicappearance. In shape they arebroadly columnar, in some partsapproaching the polygonal form,and they show very distinctly,even in the inactive condition ofthe gland, two parts or zones;an inner granular zone next thelumen, and an outer clear andfinely striated zone next the base-ment membrane (fig. 552). When tlie gland is stimulated to activity the cells at first enlarge and bulge thebasement membrane ; subse
. Quain's elements of anatomy . ation of a duct in the tubularalveoli, a : the two zones in the alveolarcells are well seen. The secreting cells of the pan-creas have a very characteristicappearance. In shape they arebroadly columnar, in some partsapproaching the polygonal form,and they show very distinctly,even in the inactive condition ofthe gland, two parts or zones;an inner granular zone next thelumen, and an outer clear andfinely striated zone next the base-ment membrane (fig. 552). When tlie gland is stimulated to activity the cells at first enlarge and bulge thebasement membrane ; subsequently the granules of the inner zone become fewer-in number and aggregated near the lumen, and the outer clear zone extends overthe greater part of the cell (Heidenhain, Kiihne and Lea). Various observers after forcing injections into the alveoli of the pancreas back-wards from the duct, have seen fine intercellular canaliculi, comparable to thoseof the liver, passing from the lumen of an alveolus between the secreting Fig. 553. Fig. 553.—An alveolus op the pancreas injected fromTHE excretory DUCT (Saviotti). Highly magnified. The alveolar cells and nuclei are only faintly indicated; thoseof the duct are not represented at all. The injection is seenfilling the central cavity of the alveolus, and passing from thisin fine channels (represented by black reticulating lines) be-tween and around the cells (after Saviotti). The connective tissue of the gland, after forming a sortof external investment, penetrates betvs^een its lobes orlobules conveying the blood-vessels to all parts. Theyare not however everywhere equally numerous, for someacini are not surrounded by the capillary network. Onthe other hand in certain parts of the interalveolar tissuecollections of small cells are met with which are sur-rounded with a very close network of large convoluted capillaries. The cells inquestion look like small epithelium-cells but their meaning is entirely lymphatics
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