Pars intermedia

Pars Intermedia

Diagram of the pituitary gland showing the pars intermedia.

The pars intermedia is a part of the pituitary gland, which is an important endocrine organ located at the base of the brain. The pituitary gland is divided into three distinct parts: the anterior pituitary (adenohypophysis), the posterior pituitary (neurohypophysis), and the pars intermedia.

Structure

The pars intermedia is a thin layer of tissue situated between the anterior and posterior lobes of the pituitary gland. It is often considered a part of the anterior pituitary due to its embryological origin from the Rathke's pouch.

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Histological section of the pituitary gland showing the pars intermedia.

Histologically, the pars intermedia is composed of basophilic cells and colloid-filled cysts. These cysts are remnants of the Rathke's pouch and are characteristic of this region.

Function

The primary function of the pars intermedia is the production of melanocyte-stimulating hormone (MSH). MSH is involved in the regulation of skin pigmentation in some animals, although its role in humans is less clear. In humans, the pars intermedia is often rudimentary and its function is not as prominent as in other species.

Clinical Significance

In some animals, the pars intermedia plays a significant role in the regulation of melanin production and can affect skin color changes. Disorders of the pars intermedia can lead to conditions such as Cushing's disease in horses, where there is an overproduction of hormones due to pituitary dysfunction.

In humans, the pars intermedia is not commonly associated with major endocrine disorders, but its role in the overall function of the pituitary gland is still a subject of research.

Related Pages

• Pituitary gland
• Anterior pituitary
• Posterior pituitary
• Melanocyte-stimulating hormone
• Rathke's pouch