Which of the following statements concerning Hassall corpuscles is true?
**Core Concept**
Hassall corpuscles are structures found in the medulla of the thymus, composed of tightly packed whorls of epithelial cells that are thought to be involved in the maturation and selection of T lymphocytes.
**Why the Correct Answer is Right**
Hassall corpuscles are characterized by their distinctive appearance under light microscopy, with concentric whorls of squamous epithelial cells that are often surrounded by a clear space. The cells in Hassall corpuscles are thought to be involved in the process of negative selection of T cells, where self-reactive T cells are eliminated to prevent autoimmune disease. The exact mechanism of Hassall corpuscle function is still not fully understood, but it is thought to involve the expression of specific molecules on the surface of the epithelial cells that interact with T cells.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Hassall corpuscles are not involved in the production of antibodies. Antibody production occurs in B cells, which mature and mature in the bone marrow and lymphoid organs other than the thymus.
**Option B:** This option is incorrect because the function of Hassall corpuscles is not related to the regulation of calcium levels in the body. Calcium homeostasis is maintained by the parathyroid glands, kidneys, and bones.
**Option C:** This option is incorrect because Hassall corpuscles are not a type of immune cell. They are a structure composed of epithelial cells that are thought to be involved in the maturation and selection of T cells.
**Clinical Pearl / High-Yield Fact**
Hassall corpuscles are a characteristic feature of thymic development and are often seen in histological sections of the thymus. They are an important landmark for pathologists to identify in the diagnosis of thymic disorders.
**Correct Answer:** C.