The Golgi apparatus of rat small intestinal abortive cells. II. Morphology and cytochemical staining pattern during cell differentiation.

Differentiation of small intestinal absorptive cells is accompanied by morphological alterations of the Golgi apparatus which reflect the extension of its functional tasks. Golgi stacks of undifferentiated crypt cells are composed of a group of 4-7 cisternae with decreasing luminal width from one side (cis face) to the other side (trans face). In maturing cells of the upper crypt region vacuolar-like dilatations of cisternae become prominent. In mature absorptive cells dilated cisternae predominantly localized at the cis side contain lipoprotein particles thus reflecting their engagement in processing and packaging of lipoproteins. In the proximal small intestine in contrast to distal small intestinal regions, the cytochemical staining pattern of Golgi stacks after localization of thiamine pyrophosphatase, inosine diphosphatase and acid phosphatase alters coincidently with cell differentiation. In undifferentiated crypt cells only few trans Golgi cisternae exhibit reaction product. Mature absorptive cells show all cisternae strongly reactive for thiamine pyrophosphatase and inosine diphosphatase, and the majority of cisternae reactive for acid phosphatase. The alterations in the Golgi apparatus reaction pattern after localization of enzymes, assumed to be active in glycosylation (Tartakoff, 1980; Farquhar and Palade, 1981; Roth and Berger, 1982), may express alterations in the functional tasks during cell differentiation, and may reflect differences in the kinetics of glycosylated plasma membrane and lysosomal constituents between immature crypt cells and mature absorptive cells.