A 45-year-old woman comes to her physician complaining of nervousness and an unexplained weight loss of 25 pounds over the last 3 months, despite that she is not dieting or exercising. On her physical examination, the doctor notices protruding eyes, her skin is moist and warm and her fingers have a tremor. Compared to a normal individual, the biopsy of her thyroid gland would most likely reveal which of the following?