Nanozoomer 2ht

Transversal or longitudinal cryosections (8 μm) of TA and diaphragm or 5 μm from paraffin-embedded liver or kidney were prepared, fixed and stained by Haematoxylin and Eosin (H&E) or succinate dehydrogenase (SDH). Sections were imaged with the Hamamatsu NanoZoomer 2HT slide-scanner. The percentage of TA muscle fibres with centralized or internalized nuclei was counted using the cell counter plugin in Fiji image analysis software. The fibre area was measured using the Fiji software.

Rehydrated sections were subjected to antigen retrieval by microwaving 2 × 8 min at 650 W in citric acid buffer (0.01 M, pH 6) followed by 10 min cooling in citric acid buffer and 20 min washing under cold tap water. Washed slides were incubated 10 min in 3% hydrogen peroxide prior to 10 min washing in PBS supplemented with 0.25% Triton X100 (PBS‐T). Slides were incubated over‐night at 4°C with primary antibody against the pan neuronal marker HuC/HuD (A‐21271, Thermo Fisher Scientific, SE, RRID AB_221448, (Cheng et al., 2016 (link))) diluted 1:400 in PBS with 0.25% BSA. Sections were washed 3 × 10 min in PBS‐T followed by 1 h incubation with SignalStain boost‐detection HRP‐mouse (8125S, Cell Signaling, USA, RRID AB_10547893). Slides were washed 3 × 10 min in PBS‐T followed by development for 1 min with DAB reagent (sk‐4100, Vector, USA, RRID AB_2336382). Slides were washed 10 min under running tap water before being submerged 30 s in hematoxylin for counterstaining. Following counterstaining slides were washed 10 min under running tap water and dehydrated by stepwise washes in increasing grades of ethanol and xylene before being mounted with Pertex™ (Histolab, SE). Slides were scanned on a Nanozoomer 2HT (Hamamatsu, JP) in brightfield mode with 20x objective and analyzed using QuPath software (Bankhead et al., 2017 (link)).