Neurohypophysis

• Neurohypophysis consists of what?

  pars nervosa and infundibular stalk
• What is the MOST ABUNDANT CELL TYPE in neurohypophysis?

  Pituicytes
• Neurosecretory or Herring Bodies: axonal dilations where ADH and oxytocin accumulate
• Neurosecretory or Herring Bodies are faintly what?

  Eosinophilic
• Vasopressin or ADH: Increases water permeability of renal collecting ducts
• Oxytocin: Stimulates contraction of mammary gland myoepithelial cells and uterine smooth muscle
• VASOPRESSIN and OXYTOCIN are NEUROPEPTIDES that are synthesized in the HYPOTHALAMUS and are secreted to the NEUROHYPOPHYSIS
• The pars nervosa of the posterior pituitary consists of modified NEURAL tissues.
• Pars nervosa contains UNMYELINATED axons supported and sheathed by glia cells called PITUICYTES.
• The axons in pars nervosa originate from the SUPRAOPTIC and PARAVENTRICULAR hypothalamic nuclei.
• In pars nervosa, SWELLINGS called neurosecretory (Herring) bodies are present along the axons.
• Upon neural STIMULATION, neurosecretory bodies release either oxytocin or vasopressin.
• Released hormones are up by CAPILLARIES for distribution throughout the body.