Cytokeratin 10

Hydrogels were fixed using Bouin's fixative (Sigma-Aldrich) for 1 h and watered with tap water for several hours. Gels were embedded into paraffin and sections of 5 μm were prepared.
Hemalaun–eosin staining was performed according to a standard staining procedure. Hemalaun stains the cell nuclei blue, and eosin interacts with eosinophilic structures like the cytoplasm for it to be shown in red.
For antibody staining, deparaffinization was done according to a standard protocol. Sections were heat demasked with a target retrieval solution pH 9 (Dako) for 20 min in a preheated steamer (Braun). Samples were permeabilized with Triton X-100 for 10 min and then blocked with 3% BSA in PBS⁺ for 30 min. Primary antibody (Perilipin A: 1:200; Sigma-Aldrich), cytokeratin 10 (1:500), and cytokeratin 14 (1:600; both Santa Cruz) were diluted with an antibody diluent (Dako) and incubated overnight at 4°C. For detection, a peroxidase-based system from Dako (EnVision+System-HRP) was applied. A secondary antibody conjugated with an HRP-labeled polymer (Dako) was used and slides were incubated for 30 min at room temperature. The staining reaction was performed with diaminobencidine (DAB, DCS) and slides were counterstained with Mayer's hematoxylin (Dako). The sections were covered with Aquatex (Merck Millipore) and a coverslip and analyzed with a light microscope (Zeiss).