Pituitary Gland

Pituitary Gland

1. Anterior (Adenohypophysis)

   • Pars Tuberalis
   • Origin: Oropharynx (Rathke's Pouch) Oral Ectoderm
   • Composition: Cellular
   • Pars Indermedia
     • MSH: alpha melanocyte producing hormone
     • Colloid: filled cystic cavities
     • Lined by basophilic cuboidal cells
     • Origin: Remnants of Rathke's Pouch
   • Pars Distalis
     • Chromophobes (50%)
       • stem cells, support, degranulated cells
     • Chromophils (50%)
       • Acidophils
         • Somatotrophs
           • Make: Growth Hormone :GH Long bones and Liver
             • Inhibition: Somatostatin
         • Mammotrophs/ Lactotrophs
           • Make: Prolactin (PRL)
             • Inhibition: Dopamine
       • Basophils
         • Gonadotropes (10%)
           • Make: FSH & LH
         • Corticotropes (15-20%)
           • Make: ACTH
             • ADRENAL GLAND
               • Cortex 90%
                 • Derived from Mesoderm
                 • Zona Glomerulosa 15%
                   • Aldosterone (mineralocorticoid)
                     • Regulated by Angiotensin II
                       • Water and electrolyte balance by reabsorbing water and sodium
                   • Cortical arteriole
                 • Zona Fasciculata 80%
                   • Produce Cortisol (Glucocorticoid) and Androgens (DHEA)
                     • increase protein, carbohydrate and fat metabolism, suppress immune function
                       • Regulated by ACTH
                   • Spongiocytes
                     • Accumulated lipid droplets, well developed sER & mitrochondria
                       • Close proximity to fenestrated capilaries
                   • Adrenocortical Sinusoid
                 • Zona Reticularis 5%
                   • SAME
                   • Medullary Arteriole
               • Medulla
                 • Derived from Neural Crest
                 • Chromaffin Cells
                   • Adrenaline & nor adrenaline ( catecholamines)
                     • Modified postganglionic sympathetic neurons
                       • Released hormones into fenestrated capilaries
                         • Receptors: Chromogranins
                 • Ganglion Cells
                   • Axonal processes extend into cortex and modulate the secretion •Innervate blood vessels of cortex
               • 2 in superior lobes of kidney
         • Thryotropes (5%)
           • Make: TSH
         • All trophic hormones

2. Posterior (Neurohypophysis)

   • Origin: Floor of Diancephalon
   • Composition: Axonal
   • 2 hormones produced in hypothalamus, transported along hypothalamo-hypophyseal tract, and stored in HERRING BODIES (axon dilations)
     • Supraoptic Nucleus
       • ADH
         • Increases BP via vasoconstriction & reabsorption of water
           • Inhibition can cause diabetes insipitous-watery urine
     • Paraventricular Nucleus
       • Oxytocin
         • Neurophysin carrier protein holds on to Herring bodies
         • Milk release and uterine contraction
   • Pituiciytes (glial like cells) 25%
   • Fenestrated Capilaries

3. PANCRE