Stereological analysis of the guinea pig pancreas during postnatal development

ABSTRACT

The postnatal development of the guinea pig pancreas (Cavia porcellus) from 2 to 140 days old was studied stereologically by light microscopy. During this period, the pancreatic volume increased 805 percent. The compartmental volumes of the acini, intercalated ducts, excretory ducts, islets of Langerhans and stroma increased 756 percent, 1,372 percent, 1,591 percent, 3,393 percent and 793 percent, respectively, whereas the total external surfaces of the acini, intercalated ducts and excretory ducts increased 542 percent, 1,667 percent and 1,002 percent, respectively. This growth involved increases of 361 percent, 74 percent, 1,355 percent and 673 percent in the total number of acinar, centroacinar, intercalated duct and excretory duct cells, respectively. In the same period, the mean volume of acinar cells increased 210 percent. These results indicate that the growth of the acinar compartmental volume involves a significant proliferative activity of the acinar cells and an increase in the individual cell volume. Analysis of the surface-to-volume ratio during this growth showed that the acini increased significantly in size. On the other hand, the growth of the parenchymal structures was accompanied by a reduction on interacinar connective tissue spaces and by the final organization of the interlobar and interlobular septa.