QS Study

Pituitary Gland is a small endocrine gland situated in the hypophyseal fossa in relation to the base of the brain. It is a part of our endocrine system. Its major purpose is to emit hormones into your bloodstream. It secretes hormones that control the actions of other endocrine organs and various tissues around the body.

Histology of pituitary gland

The pituitary gland has two parts –

(A) Adenohypophysis: It is highly cellular and occasionally presents intra-glandular cleft. The part behind the cleft is known as pars intermedia. It includes –

  1. Anterior lobe.
  2. Intermediate lobe.
  3. Tuberal lobe.

(B) Neurohypophysis: It is continuous above with the infundibulum. It includes –

  1. Posterior lobe.
  2. Infundibular stem.
  3. Median eminence.

Histology of pituitary gland

Fig: The normal pituitary gland is seen here at low magnification, with the neurohypophysis at the left and the adenohypophysis at the right.

Anterior lobe:

(A) Chromophilic cells

(1) Acidophils

  1. Somatotrophs: Secrete growth hormone:
  2. Mammotrophs: Secrete lactogenic hormone.
  3. Corticotrophs: Secrete ACTH.

(2) Basophils –

  1. Thyrotrophs: Secrete TSH.
  2. Gonadotrophs: Secrete FSH.
  3. Luteotrophs: Secrete LH.

(B) Chromophobic cells: Represent the non-secretory phase of the other cell types or their precursors.

Intermediate lobe: Made up of numerous basophil cells & chromophobe cells surrounding masses of colloid material. It secretes the melanocyte stimulating hormone (MSH).

Posterior lobe: Composed of –

  1. Large numbers of non-myelinated fibers &
  2. Modified neurological cells, called pituicytes.

Secretory hormones:

  1. Vasopressin (ADH).
  2. Oxytocin.

Development of pituitary gland

(A) Adenohypophysis: Develops from the Rathke’s pouch, which is formed by the ectodermal out pocketing from the stomodeum in front of the buccopharyngeal membrane.

(B) Neurohypophysis: Develops from the down growth of the floor of the diencephalon. It is neuroectodermal.

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