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Physiology

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Endocrinology

Question
17 out of 19
 

In the neurohypophysis, secretory granules accumulate in:



A Pituicytes
B Nerve endings

C Intercellular spaces
D Capillary endothelium

Ans. B Nerve endings

1. Pituitary eland (Hypophysis) : two portions:­

a. Anterior Pituitary (or Adenohypophysis): -originates from Rathke's pouch (which is an embryonic invagination of the pharyngeal epithelium)

b. Posterior pituitary (or Neurohypophysis) which is an outgrowth of the hypothalamus.

2. Neurohypophysis

a. Connects with Hypothalamus via nerve fibers forming track called hypo-thalamico­Hypophysial tract"

b. Fibers of tract contain granules called neurosecretory granules or Gomori bodies which are stored, the hormones.

c. Two hormones of neurohypophysisvasopressin(ADH) and oxytocin. "These hormones are synthesized in the cell bodies of the magnocellular neurons in the supra-optic nuclei (mainly ADH) and paraventricular nuclei (mainly oxytocin) of the hypothalamus and transported in combination with "carrier" protein called neurophysin, down the axons of these neurons to their nerve endings in the neurohypohysis.

3. Adenohypophysis: - histologically consists of 30-40% somatotropes (Acidophils, secretes GH), 20% of corticotropes (ACTH) and 3 to 5% of thyrotropes (TSH), Gonadotropes (LH, FSH) and lactotropes (protectin)

4. Pituicytes: - Neurohypophsis composed mainly of glial like cells called pituicytes. The pituicytes do not secrete hormones, they act simply as a supporting structure for large number of terminal nerve fibers and terminal nerve endings.

Endocrinology Flashcard List

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