Volume Density, Distribution, and Ultrastructure of Secretory and Basolateral Membranes and Mitochondria Predict Parietal Cell Secretory (Dys)function
Figure 4
(a) AE2/ parietal cells showed a reduction in TV, canalicular and mitochondrial Vd, and, seen at higher magnification, cytoplasm contained occasional polysomes but generally reduced numbers of organelles (compared to WT and NHE2/ (see Figure 1)). Microvilli were mostly confined to the apical membrane, incipient canaliculi were equivocally identified, and electron-dense material often filled the gastric gland lumen (G). (b) The GHKA/ parietal cells showed short microvilli, round vesicles instead of TV, cytoplasmic glycogen, frequent canalicular dilatation, and occasionally, large mitochondria with whorled cristi. (c) and (d). The two genotypes that seemed to have the most organelle-depleted cytoplasm were the NHE4/ (c) and the NHE2/ AE2/ double KO (d). Parietal cells in both of these genotypes were very sparsely inter-populated with organelles, having significant reductions in Vd of both membranes and mitochondria. (e) NHE2/ GHKA/ parietal cells were quite similar to the GHKA/ single knockout. The latter two were the only genotypes which showed cytoplasmic glycogen or whorled cristi in mitochondria, and short stubby microvilli. For all panels: arrow heads: mitochondria; white arrowheads: mitochondria with whorled cristi; arrows: canaliculi, N: nucleus; Z (white) zymogen granule.
