Circumventricular Organs - Succinct Presentation - Sanjoy Sanyal


Published on

Circumventricular Organs (System) have been well studied, starting with Paul Ehrlich work with Trypan Blue in 1882, and research on their functions is still going on. However, Neuroscience medical students find it difficult to understand them. This short PPTX is meant to succinctly explain the Circumventricular Organs.

Short Video clips pertaining to each CV Organ on a human brain specimen, created and uploaded on YouTube by the author, Dr Sanjoy Sanyal, Professor and Course Director of Neuroscience, are embedded between slides, to provide a narrative highlight to what is mentioned in the slides.

Tags: Median Eminence, Tuber Cinereum, Arcuate Nucleus, Organum Vasculosum, Lamina Terminalis, Subfornical Organ, Pineal, Epiphysea, Subcommissural Organ, Area Postrema, Supraoptic Nucleus, Suprachiasmatic nucleus, Preoptic nucleus

"Copyright Disclaimer Under Section 107 of the Copyright Act 1976, allowance is made for "fair use" for purposes such as criticism, comment, news reporting, teaching, scholarship, and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use."

Published in: Education
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Circumventricular Organs - Succinct Presentation - Sanjoy Sanyal

  1. 1. Dr Sanjoy Sanyal MBBS, MS (Surgery), MSc (Royal College of Surgeons of Edinburgh), ADPHA Professor and Course Director of Neuroscience – FCM-III Neurology
  2. 2. Paul Ehrlich (1882) After IV injection of Trypan Blue, most Brain areas did not get stained These areas are inside the BBB Some areas of Brain did get stained These structures are outside the BBB; i.e. they do not have a BBB
  3. 3. Tight Junctions (Claudin / Occludin) between Endothelial Cells They form a continuous Lipid Bi-layer Continuous Basement Membrane outside Astrocyte Podocytes form complete circle Red arrows indicate lack of permeability
  4. 4. Highly Vascularized Fenestrations of Endothelial Cells Permeable Basement Membrane Astrocyte Podocytes do not form complete circle Red arrows indicate permeability Exception: Sub- Commissural Organ has Non- fenestrated Capillaries
  5. 5. Tancytes line the Floor of 3rd Ventricle Body of Tancyte is in contact with CSF Multiple Foot-Process extend towards adjacent Capillary Provides conduit between CSF and Blood Tancytes play important role in certain Non-BBB areas
  6. 6.  Most Non-BBB areas are around 3rd Ventricle, and one in 4th Ventricle  They are called Circumventricular Organs  They are bathed by CSF and are also in contact with Capillaries  Median Eminence of Tuber Cinereum  Organum Vasculosum of Lamina Terminalis  Sub-Fornical Organ  Pineal Gland  Sub-Commissural Organ  Area Postrema  Wall of Optic Recess  Posterior Lobe of Pituitary
  7. 7. Chemosensitive Organs Allow ‘sampling’ of Blood Endocrine Feedback and Regulation Homeostasis Metabolic Regulation Fluid Electrolyte Balance Detect Toxins in Blood CSF Circulation(?)
  8. 8. Tancytes line the Floor of 3rd Ventricle and ME-TC Has Arcuate Nucleus that detects Endocrine Feedback to Hypothalamus via the Tancytes Releases RH/IH, P-IH, and maintains Basal Levels of Hormones (FSH-LH) In Floor of 3rd Ventricle: Raised Central Part of a Convex gray matter in the Ventral-most part of Hypothalamus #1
  9. 9. Has Osmoreceptors Regulates ADH release by Supraoptic Nucleus Provides Vascular Outlet for LH-RH by Pre- optic and GH-IH by Suprachiasmatic (Both are adjacent to LT) A.k.a. Vascular Organ of Lamina Terminalis #2
  10. 10. On inferior surface of Fornix, at level of Foramen of Monroe (#3) Angiotensin II Receptors Neurons from SFO project to SO Nucleus and OV-LT (Both are Osmoreceptors) Fluid Electrolyte balance
  11. 11. Pinealocytes (Epiphyseal Cells) #4 Highly Vascular Fenestrated Capillary Release Melatonin into 3rd Ventricle Transported by Tancytes in Floor of 3rd Ventricle Act on Pituitary Gland
  12. 12. Special Epithelial / Glial Cells Non-fenestrated Capillaries Functions: (a) Circulation of CSF (Hydrocephalus); (b) Clearance of certain compounds (?) Below Posterior Commissure #5 At 3rd Ventricle– Aqueduct of Sylvius Junction
  13. 13.  Modified Astrocyte-like Neurons  Fenestrated Capillaries  5-HT3 Receptors (Excitatory Ionotropic)  Induces Vomiting from Morphine, Blood 5-HT  Gets Afferents from CTZ and GIT  Plays Role in Food Intake / CVS Control  In Floor of 4th Ventricle, Between Vagal Triangle and Inferolateral margin of Rhomboid Fossa, just Rostral to