Figure 3
From: Insights into replicative senescence of human testicular peritubular cells
Selected FIB/SEM micrographs of a series of HTPCs from early (a–d) and advanced passages (a’–d’). The numbers (upper right) indicate the selected micrographs from the series. In the early passage the HTPC shows contact sites of ER with a branched mitochondrion (M) with several cross sections within one micrograph (4 nm isovoxel). Vacuoles (V) form within the mitochondrial matrix, leading to swellings (b; circle/transparent magenta) with some cristae still visible (a, arrows). Sheets of ER are attached to the mitochondrial network, noticeable after 3D reconstruction (c,d). The advanced passage exhibits numerous lens shaped vacuoles (a’; asterisks; voxel size: 7.5 × 7.5 × 14 nm). Strands of rough ER are connected at both ends to the vacuoles (a’, circles). Electron dense inclusions within the vacuole were identified as lysosomes (a’, arrow), when following the FIB/SEM series. Lysosomes (Ly) are connected to strands of ER at multiple sites (a’; squares). 3Dreconstruction of vacuoles (V) and lysosomes (Ly) show that they form clusters connected to each other (b’; arrow). The ER forms large sheets, best visible in top view (c’) compared to the FIB/SEM block face micrographs (a’). The ER membrane is in continuity with the vacuole membrane (c’; rectangle). The mitochondrion (M) shown is also locally fused with smaller and larger vacuoles (d’; circles).
