1. The effect of age and androgen level on enzyme activity and cellular structure has been determined in the mouse submaxillary gland.2. A new protease which resembles chymotrypsin in its substrate specificity has been characterized in the gland.3. Activity of the chymotrypsin- and trypsin-like proteases and renin increased considerably in male mice concomitantly with proliferation of granules in the secretory tubules of the gland.4. The androgen dependence of the chymotrypsin- and trypsin-like enzymes, renin and the organelles within the secretory tubules was confirmed in castrated male mice. The activity of these enzymes increased and correlated with the appearance of intracellular granules in the secretory tubules when the castrated male mice and in addition female mice were treated with testosterone preparations.5. Kallikrein, a closely related protease, and amylase increased in activity with age but showed no sex-linked differences.6. The results suggest that kallikrein is sequestered in acinar cells whereas the androgen-dependent enzymes (chymotrypsin, trypsin and renin) are located in the secretory tubules.

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SUMMARY1. Subcellular organelles containing kallikrein (-ogen), trypsinogen and amylase have been isolated from homogenates of dog pancreas and found on discontinuous sucrose density-gradients to equilibrate with 1-7-1-775 M sucrose.2. The electron microscopic appearance of the isolated enzyme-containing organelles appeared to be identical with that of the secretary (zymogen) granules seen in sitU in the acinar cells of the pancreas.3. The sequence of events associated with the storage and intracellular transport of pancreatic secretary enzymes is reviewed. The results obtained in this study have been used to delineate the probable intracellular pathway taken by kallikrein, trypsin and amylase from synthesis to secretion.4. The physiological role of the glandular kallikreins is discussed.