Which of the following is NOT one of the major endocrine glands?

The kidneys are primarily recognized for their role in filtering blood and regulating fluid balance, electrolytes, and waste excretion; they are not classified as one of the major endocrine glands. While kidneys do have some endocrine functions, such as the production of renin and erythropoietin, they are not predominantly known for endocrine activities like other glands.

In contrast, the thyroid gland is essential for regulating metabolism, the adrenal glands produce hormones involved in stress response and metabolism, and the pancreas plays a crucial role in regulating blood glucose levels through the secretion of insulin and glucagon. Each of these glands is vital for maintaining various physiological processes and hormonal balance in the body, making them key players in the endocrine system.