Fig. 5.

Histological tracking of regenerated tissue shows mature adipocytes/fat formation in seeded groups at 12 and 18 months. (a) H&E images at 12 (top) and 18 months (bottom) show that fat formation was present in seeded groups. The silk sponge stains a dark purple and is visible in all groups. At 12 months, the silk sponge walls began to fracture as the sponge degraded. In some sections, dark, or black deposits of hemosiderin were seen (see Supplementary Fig. 2). Scale bar – 100 µm, inset – 200 µm. (b) Masson’s Trichrome staining for tissue organization at 12 (top) and 18 months (bottom). The silk sponge stains red and is visible in all groups. The cellularity (nuclei stain dark or black), decreased from 12 to 18 months in all groups, and then is replaced with a well-organized collagenous matrix (blue). Scale bar – 100 µm, inset – 200 µm. (c) Oil Red O (ORO) for staining mature adipocytes at 12 (top) and 18 months (bottom). The silk sponge (asterisk) stains a light purple and is visible in all groups. Areas of ORO positive staining are pointed to with a red arrow. The lipo-seeded groups (right) stained the most densely for ORO. Scale bar – 200 µm. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)