The gums bleed easily around the teeth and the capillaries under the skin spontaneously break, producing pinpoint hemorrhages. When vitamin C concentrations drop to about one-fifth of optimal levels, symptoms of scurvy begin to appear. Insufficient collagen synthesis causes further bleeding. Muscles, including the heart muscle, degenerate. The skin becomes rough, brown, scaly and dry. Wounds do not heal because scar tissue does not form. Bone reconstruction falters; the ends of long bones become softened, malformed and painful, and fractures develop. Teeth become loose as the cartilage around them