(a) pituitary gland
The pituitary gland is called the master gland of the endocrine system. It is the gland that controls the activity of many other endocrine hormones of the endocrine system.
The thyroid gland is a vital hormone gland: It plays a major role in the metabolism, growth, and development of the human body. It helps to regulate many body functions by constantly releasing a steady amount of thyroid hormones into the bloodstream.
The pancreas is an organ located in the abdomen. It plays an essential role in converting the food we eat into fuel for the body's cells. The pancreas has two main functions: an exocrine function that helps in digestion and an endocrine function that regulates blood sugar.
The testes are two oval-shaped male reproductive glands that produce sperm and the hormone testosterone.