Which of the following is NOT an endocrine gland?

Correct option is D

An endocrine gland is a structure that secretes hormones directly into the bloodstream.

• Pituitary gland – a major endocrine gland (“master gland”)

• Parathyroid gland – secretes parathyroid hormone

• Pancreas – has an endocrine part (Islets of Langerhans) that secretes insulin and glucagon

The hypothalamus, although it produces releasing and inhibiting hormones, is primarily a part of the brain (neuroendocrine structure) and not classified as a pure endocrine gland.

Therefore, the correct answer is Hypothalamus.