Localization of a bound lipid fraction in the pancreas of the mouse.

The pancreas of adult and old mice of various ages has been shown to contain a lipid fraction which is not normally stainable, but which is unmasked by the action of the lipid-solvent methanol: chloroform (1:2 v/v) and hence becomes stainable by the acid haematein reaction. This fraction seems to be contained in the zymogen granules of adult and old mice, but is absent from the pancreas of tto 2-week-old animals.