Golgi Complex from Mammotroph of Lactating Female Rat Pituitary. In this image the content of two immature secretory granules (ISG) is condensing within the last Golgi cisterna on the trans-face. The cis-face of the Golgi is also apparent. Additionally, a mature secretory granule formed from the aggregation of several ISG is present on the trans-side of the Golgi. Image presented as a layered tiff with the first image the unlabeled image and the second image the labeled version. Bar=0.5 microns. The site of condensation and packaging of regulated secretory proteins was studied by the Farquhar group in a number of anterior pituitary cells to determine if the process of concentration and packaging of secretory proteins occurs in the same way as in exocrine cells (e.g., the exocrine pancreas) where concentration in condensing vacuoles was described. The pituitary of a lactating female rat was perfused with chilled 1.5% glutaraldehyde in 0.067 M cacodylate buffer, pH 7.4, containing 1% sucrose. The pituitary was removed from the rat and placed in fresh fixative for an additional 2 hours. Postfixation was with 1% osmium tetroxide in acetate-veronal buffer, pH 7.4. The sample was dehydrated and embedded in Epon. Sections were stained with uranyl acetate followed by lead citrate. In: Heller H, Lederis K, eds. Memoirs of the Society for Endocrinology: Subcellular Structure and Function in Endocrine Organs. Cambridge University Press; 1971;19:79-122. Annotator of EM: Marilyn G Farquhar (University of California, San Diego, CA). Annotator of EM: Kathryn E Howell (University of Colorado School of Medicine, Aurora, CO). Original resource: lantern slide (3.25 x 4 inches).