Pituitary gland

The pituitary gland is known as the “master endocrine gland.” This gland receives stimulatory input from the hypothalamus and secretes multiple different hormones , which target multiple different end organs and have wide-ranging effects throughout the body.

Location

• Located in the sella turcica of the sphenoid bone
• Just below the optic chiasm
• Connected to the hypothalamus by the pituitary stalk
• Lies outside the dura

General structure  Consists of two major parts:

• Anterior pituitary gland (adenohypophysis): develops from oral ectoderm (Rathke pouch) and constitutes 80% of the pituitary.

• Posterior pituitary gland (neurohypophysis): develops from neural ectoderm

Development

Anterior pituitary:

• Develops from outpocket of the oropharynx (Rathke pouch)
• Derived from oral ectoderm

Posterior pituitary:

• Downgrowth from the 3rd ventricle of the brain
• Derived from neuroectoderm

Gross anatomy

Major components of the pituitary gland include:

• Pars distalis: the bulk of the glandular portion/anterior pituitary
• Pars nervosa: the bulk of the neurosecretory portion/posterior pituitary
• Pars intermedia: a thin wedge separating the pars distalis from the pars nervosa
• Pituitary stalk:
  • Connects the pea-like lobes of the pituitary (the pars distalis and the pars nervosa) to the hypothalamus
  • Consists of: 
    • Infundibulum: arises from the posterior pars nervosa
    • Pars tuberalis: arises from the anterior pars distalis and wraps around the infundibulum

• The anterior pituitary gland is responsible for the release of:
  1. Follicle-stimulating hormone (FSH)
  2. Luteinizing hormone (LH)
  3. Adrenocorticotropic hormone (ACTH)
  4. Thyroid-stimulating hormone (TSH)
  5. Prolactin (PRL)
  6. Growth hormone (GH)

• The posterior pituitary gland is responsible for the storage/release (تخزن الهرمونات ولا تقوم بتصنيعها) of the antiduiretic hormone (ADH) and oxytocin.