Pituitary gland

The pituitary gland, also called the hypophysis cerebri, is an important endocrine gland found in vertebrates. In humans, it sits at the base of the brain, attached to the hypothalamus. This small gland helps control many body functions by making special chemicals called hormones.

The pituitary gland is located in a little dip in the skull called the sella turcica, in a place known as the hypophyseal fossa. It is about the size of a kidney bean, roughly 1 centimeter across and weighs just under one gram.

The pituitary gland has two main parts: the anterior lobe and the posterior lobe. The anterior lobe makes and releases several important hormones. The posterior lobe stores and releases hormones that are made in the hypothalamus.

Hormones from the pituitary gland help control many body processes. They help with growth, blood pressure, energy use, and how the sex organs and thyroid gland work. They also help with metabolism, and parts of pregnancy, childbirth, and breastfeeding. The gland helps manage water and salt balance in the kidneys, body temperature, and even pain relief.

Structure

The pituitary gland is a small gland at the base of the brain. It sits in a bony space called the sella turcica. It has three parts: the anterior pituitary, the posterior pituitary, and an intermediate lobe. The intermediate lobe is very small in humans but is more noticeable in other animals.

The anterior pituitary makes several important hormones. It is controlled by a brain area called the hypothalamus. The posterior pituitary releases hormones that are made in the hypothalamus. These hormones travel down a stalk connecting the two areas. Both parts of the pituitary gland help control many body functions through the hormones they produce.

Main article: Anterior pituitary

Main article: Posterior pituitary

Function

The pituitary gland, also called the hypophysis, helps control many body functions by releasing special chemicals called hormones.

The front part of the pituitary gland releases hormones that manage growth, stress, reproduction, metabolism, and milk production.

The back part of the pituitary gland stores and releases hormones that help control water balance and support childbirth by helping the uterus contract. With the hypothalamus, the pituitary gland helps keep the body’s systems working well.

Main article: Pituitary gland

Development

The pituitary gland forms early when a baby is growing inside its mother. It starts as a small group of cells in the outer layer of the developing body, called the hypophyseal placode. These cells form a pouch called Rathke’s pouch, which becomes the front part of the pituitary gland. At the same time, a part of the developing brain grows downward to form the back part of the pituitary gland.

Over the next few weeks, these parts change and move into place. The front part of the pituitary starts making important hormones like growth hormone around the 12th to 16th week. By the end of the first three months, the pituitary gland is fully formed and connects to the brain, helping control many body functions.

Clinical significance

Main article: Pituitary disease

The pituitary gland helps control many body functions. If it does not work right, it can cause health problems. For example, not enough of a hormone called vasopressin can cause a condition called central diabetes insipidus. Too much growth hormone in children can make them very tall, while too much in adults can cause acromegaly. Low levels of thyroid-stimulating hormone can lead to hypothyroidism. The pituitary gland can also have tumors that are usually not cancerous, and these can change how the gland works. The gland helps the body deal with stress and its size can change based on early life and hormone levels.

History

The pituitary gland has a fascinating history. Ancient Greek physician Galen called it gland and thought it helped make nasal mucus. Later, anatomist Andreas Vesalius named it glandula pituitaria, meaning "gland in which slime drips." This is how it got the name pituitary gland.

The word hypophysis was made by German anatomist Samuel Thomas von Sömmerring. It means "under growth" and describes where the gland sits below the brain. Scientists later discovered more about what the gland actually does.

Other animals

The pituitary gland is found in all vertebrates, but it can look different in different animals. In mammals, it has a special shape. In animals like lungfish, amphibians, reptiles, and birds, it looks quite different. For example, in lungfish, the pituitary is flat, and in birds, a part of it is missing.

In fish that are not lungfish, the pituitary looks even more different. It often has a part called the intermediate lobe. Some fish, like lampreys, have a simple form of the pituitary. There are also interesting structures in other animals, like a gland in armadillos that is similar to part of the pituitary, and a structure in octopuses that works in a similar way.

Additional images

The following images help show the pituitary gland and related structures:

• Frontal view
• Pituitary and pineal glands
• Depiction of pituitary gland