The pituitary gland by virtue of its tropic hormones controls the secretory activity of other endocrine glands. Which one of the following endocrine glands can function independent of the pituitary gland?

The parathyroid gland is the correct answer because its function is regulated by the level of calcium ions in the blood rather than by hormones from the pituitary gland. When blood calcium levels drop, the parathyroid glands release parathyroid hormone to increase calcium levels. In contrast, the other glands listed are directly controlled by the pituitary. The thyroid is stimulated by Thyroid Stimulating Hormone, the gonads by Follicle Stimulating Hormone and Luteinizing Hormone, and the adrenal cortex by Adrenocorticotropic Hormone. Since the parathyroid responds directly to chemical changes in the blood, it can function independently of the pituitary gland.