Standard semiautomated rotary microtome and lighted water flotation bath

All animals were humanely euthanatized in accordance with defined experimental endpoints, and gross necropsy was performed. Tissue samples were inactivated by fixing for 72 h in 10% neutral buffered formalin. Following fixation and removal from the BSL-4 laboratory in accordance with standard operating procedures, tissue samples were routinely processed in a Tissue-Tek VIP-6 automated vacuum infiltration processor (Sakura Finetek USA, Torrance, California, USA) followed by paraffin embedding with a Tissue-Tek model TEC unit (Sakura Finetek USA, Torrance, CA, USA). Using a standard semiautomated rotary microtome and lighted water flotation bath (Leica Biosystems, Wetzlar, Germany), tissue sections were cut at a thickness of 4 µm and mounted on positively charged uncoated glass slides (ThermoFisher, Waltham, MA, USA), air-dried at room temperature, stained with hematoxylin and eosin (H&E), and coverslipped for microscopic evaluation by the pathologist.