Studies on dispersed pancreatic exocrine cells. I. Dissociation technique and morphologic characteristics of separated cells.

A procedure for dissociation of the guinea pig pancreas into individual cells is described which employs enzymatic digestion with pure collagenase, chymotrypsin, and hyaluronidase, utilizes an interposed chelation of divalent cations by EDTA, and is terminated by gentle shearing. Yields of cells are 50-60%, based on DNA recovered. The population comprises approximately 95% exocrine cells, the remainder consisting of endocrine, duct, and vascular endothelial cells. The exocrine cells, though spherical, retain the structural attributes of their in situ counterparts, including differentiation of the plasmalemma into zones corresponding to the former apical and basal plasmalemma, polarized distribution of organelles indicated by fields of zymogen granules in the cytoplasm underlying the former apex, central location of the Golgi complex, and placement of the rough endoplasmic reticulum and nucleus in the former basal pole of the cell. Electron microscope study of the effects of individual treatments used during dissociation indicates that digestion of basement membrane and collagen is solely due to collagenase activity and that separation of desmosomes (and possibly of zonulae adherentes) results only from exposure to low [Ca(++)] and EDTA and is not effected by the enzymes used. Gap junctions are resistant to enzymes and EDTA; tight junctions resist enzyme treatment but undergo rearrangement upon exposure to EDTA. Both junctions require mechanical shear for complete cell separation. Neither chymotrypsin nor hyaluronidase produces visible alterations in stromal or junctional elements. Dissociation requires the concerted action of enzymes, chelation of divalent cations, and mechanical shear, since the individual treatments are alone ineffective.