Further ultracytochemical analysis of rat adenohypophyseal cells: detection of two distinct enzyme activities within a single cell.

In an effort to ascertain whether a lysosomal enzyme, aryl sulphatase (ArSase), might share the same cell and, or, the same intracellular structure(s) with a histochemical Golgi apparatus marker, thiamine pyrophosphatase (TPPase), in rat pituitary mammotrophs and somatotrophs a technique for a selective demonstration of both enzyme activities within a single specimen has been developed. The technique is based on the selective dissolution of TPPase-related precipitates with 50% sulphuric acid in an ultrathin section of a pituitary specimen processed consecutively for ArSase and TPPase. The analysis of pairs of micrographs displaying the same structures before and after treatment with sulphuric acid has shown that TPPase-related precipitates are located mainly in the trans-Golgi lamellae while ArSase-related precipitates (resistant to sulphuric acid) could be found in both GERL and its derivatives (lysosomes, immature secretion granules) and in the TPPase-reactive trans-Golgi pole in both cell types studied. When seen within the same dictyosome each enzyme activity resided generally within an individual Golgi lamella. Direct continuity between ArSase- and TPPase-related precipitates was also occasionally encountered. The results indicate that ArSase and TPPase activities can share the trans-cisternae of the Golgi apparatus in mammotrophs and somatotrophs of rat pituitary.