|Congenital Adrenal hyperplasia
|Primary hyperaldosteronism (Conn's syndrome)
|McCune Albright syndrome
| Male Infertility
| Sheehan's syndrome
- Adenohypophysis - Anterior pituitary descends from Rathke's pouch
- Neurohypophysis - Posterior pituitary ios a direct extension from the hypothalamus, connected to it via the infundibular stalk, which is also considered part of the neurohypophysis
- The lobes are separated by a pars Intermedia.
- Two lobes of different embryological origins - anterior and smaller posterior lobe separated by the pars Intermedia.
- Posteriorly the pituitary connects to the tuber cinereum on the floor of the 3rd ventricle by a hollow infundibulum called the pituitary stalk
- Pituitary lies in the cavity of the pituitary fossa (sella turcica) covered by the diaphragma sellae
- Inferiorly is the body of the sphenoid and sphenoid sinus below and laterally lies the cavernous sinus and carotid artery.
- Optic chiasma lies above and in front of the infundibulum.
- Cavernous sinus contains internal carotid arteries and cranial nerves III, IV and VI and V1 and V2.
- Above lies the optic chiasma, hypothalamus, pituitary stalk.
- Anterior lobe contains chromophobe, eosinophilic and basophilic cells and releases the following hormones ( for clinical purposes)
- Posterior lobe is Supplied by axons that originate in the supraoptic and paraventricular nuclei
- Oxytocin and antidiuretic hormones are synthesized in the hypothalamus and travel down the stalk to be released in the posterior pituitary.
Anterior lobe (adenohypophysis)
- ACTH can split to form Melanocyte stimulating hormone (MSH) and Corticotrophin like peptide. Release stimulated by corticotrophin-releasing hormone from the hypothalamus. Stimulates Adrenal glands to release Steroids.Pro-opiomelanocortin (POMC) splits to form ACTH + lipotropin
- TSH - glycopeptide release due to TRH. Stimulated thyroid to release T3 and T4
- LH - alpha and beta chain polypeptides. Females stimulate ovulation and ovarian oestrogen and progesterone secretion. Males stimulated testosterone secretion from Leydig cells in the testes. Under control of hypothalamic gonadotrophin-releasing hormone.
- FSH - alpha and beta chain polypeptides. Females stimulated follicular development. In mean stimulates spermatogenesis. Under control of hypothalamic gonadotrophin-releasing hormone.
- GH - glycopeptide, released mainly at night, pulsatile. Results in skeletal growth.
- Prolactin - molecule similar to GH. The release is inhibited by Dopamine. Elevated in pregnancy and with lactation and stress and hypoglycaemia and post-seizure. Prolactin stimulates breast milk production.
Posterior lobe (Neurohypophysis)
- Vasopressin (ADH) - protein composed of 8 amino acids. Increases permeability of collecting ducts through its action on aquaporins. The release is due to stress, morphine, trauma, surgery and increases in osmolality detected by hypothalamic osmoreceptors.
- Oxytocin - Actions on breast and uterus such as stimulating uterine contractions whilst in labour.
- This is the boundary between the anterior and posterior lobes of the pituitary. It contains colloid-filled cysts and two types of cells - basophils and chromophobes. The cysts are the remainder of Rathke’s pouch
- The main function of this pituitary section is to manufacture the MSH (Melanocyte-stimulating hormone), releases the pigment Melanin into the pigment cells (melanocytes) of the skin