Anatomical model of a uterus during pregnancy (8 weeks), before treatment. The exterior shows the shrinkage, cracks, and fading of the paint and varnish layers. Compare the exterior with the interior of this uterus model. Age, light, and changes in relative humidity have caused the exterior's paint and varnish layers to shrink and crack, and the colors to fade. This has produced several areas where the paint layer lifted and separated from the surface of the papier-mâché. The interiors of the models reveal their original beauty. Exposed to less light and buffered from changes in relative humidity, the interiors remain smooth, with very few cracks and with vivid colors.   Anatomical model of a uterus during pregnancy (8 weeks) open, before treatment. The colors and anatomical details remain crisp and clear on the interior.