Fig. 4: Insertion of MP20 into fiber cell membranes correlates with the constriction of the extracellular space in vivo.

Human lens labeled with a WGA b MP20 c extracellular dye. d Overlay of (b, c). Image montage of the outer cortical region of cryosection taken through the equator of a human donor lenses organ cultured in the extracellular space marker Texas Red-dextran for 6 h. a WGA-TRITC labeling to highlight the change in membrane morphology as fiber cells differentiate and become internalized into the adult nucleus. b MP20 labeling showing the shift from the cytoplasm to the membrane. c Texas Red-dextran labeling of the extracellular space. White line showing where the dye stops and the extracellular spaces become restricted. d Double labeling of MP20 (green) and Texas Red-dextran (red) showing the formation of the extracellular diffusion barrier corelates with the membrane insertion of MP20 into the membranes of fiber cells in the adult nucleus. e Schematic diagram (not drawn to scale) summarizing changes in the morphology of differentiating fiber cells in the outer cortex of the human lens. DF differentiating fiber cells, RZ remodeling zone, TZ transition zone.