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. 2023 Jan 20;12:e80135. doi: 10.7554/eLife.80135

Figure 6. Ultrastructure of late endocytic and lysosomal organelles in CaCo2 wildtype (WT) cells versus selected knockout (KO) cell lines of cryo-fixed 18-day-old polarized filter cultures under steady-state conditions.

Figure 6.

(A, B) WT CaCo2 cells with normal endosomes and lysosomes: multivesicular bodies (MVBs) with varying contents (regarding intraluminal vesicle [ILV] number, size, and staining patterns), different types of (autophago)lysosomes (arrowheads), all filled with clearly stained, finely granular material plus membrane remnants (i.e., multilamellar bodies), and/or opaque, amorphous residues (i.e., dense-core lysosomes). Double arrowheads mark examples of inconspicuous spherical organelles with weakly stained, quite homogeneous granular contents harboring only sporadic ILVs and/or other structured components, interpreted as kind of endolysosome (Bright et al., 2016). (C) Large, poorly structured putative endolysosome (double arrowhead), virtually the predominant type of late endocytic and/or catabolic organelles in ANO8 KO at steady state. (D) Moderately sized and enlarged putative endolysosomes (double arrowheads) in PIP5K1C KO cells. (E) Enlarged putative endolysosome (arrowhead), the predominant type of late endocytic/catabolic organelles in TM9SF4 KO cells. (F) Moderately enlarged putative endolysosomes (double arrowheads) occurring together with normal lysosomes in ARHGAP33 KO cells. (G) Enlarged putative endolysosomes (double arrowheads) occurring together with slightly smaller lysosomes in MTMR2 KO cells. Arrows mark lateral microvilli. (A–G) Scale = 500 nm.