Development of the actin and the cytokeratin cytoskeletons of parietal cells during differentiation of the rat gastric mucosa

Available evidence strongly suggests that microfilaments and cytokeratin in termediate filaments (IF) play a role in the reorganization of the luminal pole required for the secretion of acid by parietal cells. To correlate the organization of both cytoskeletal systems with the differentiation of the secretory membranes of parietal cells, the distribution of F-actin and cyto keratin was studied during the ontogenic development of the rat. Primitive parietal cells were detected with parietal cells autoantibodies a nd ultrastructurally by transmission electron microscopy (TEM). The distrib ution of IF and of F-actin in differentiating parietal cells was determined using anticytokeratin antibodies and FITC-phalloidin, respectively. Develo pment of both cytoskeletal systems was followed by TEM, Ultrastructurally, parietal cells are identified from day 19 on, by the pre sence of an incipient canaliculus, which later enlarges and fills: with mic rovilli. No intracellular tubulovesicular system is observed. Using parieta l cells autoantibodies these cells are detected from day 20 on. Immunocytoc hemistry and TEM demonstrate that parietal cells possess organized cytokera tin and actin cytoskeletons, which develop further as differentiation proce eds. At birth, parietal cells show an ultrastructure and a distribution of IF and microfilaments similar to that of differentiated cells. In newly bor n rats, the F-actin cytoskeleton redistributes after suckling. This reorgan ization results from an enlargement of the canalicular lumen, filled with m icrovilli rich in actin. Thus, functional maturation of parietal cells is paralleled by, the develop ment of organized IF and F-actin cytoskeletons associated to the secretory surface. Anat Rec 255:342-352, 1999. (C) 1999 Wiley-Liss, Inc.