I discuss issues pertaining to the practice of neuropathology -- including nervous system tumors, neuroanatomy, neurodegenerative disease, muscle and nerve disorders, ophthalmologic pathology, neuro trivia, neuropathology gossip, job listings and anything else that might be of interest to a blue-collar neuropathologist.
Thursday, June 14, 2012
Best Post of January 2012: The area postrema is not the only area where the BBB is lacking
The next in our "Best of the Month" series comes from January 9, 2012:
I'll paraphrase a question posed by one of my 2nd-year students at Southern Illinois University School of Medicine:
I understand that the Area Postrema
was a site where there was increased penetrability of the blood brain barrier.
I am not sure, but thought I had come across additional sites of increased
penetrability last year in my reading. Are there other sites where there is
increased permeability of the BBB?
In pondering an answer to this question, I immediately thought of the
illustrious Dr. John Donahue, consummate neurologist, neuropathologist,
and neuroanatomist. I posed the question to him and got the following
Dr. John Donahue, Brown University, Providence, RI
"Not increased permability of the
BBB. NO BBB! Area postrema is one of the circumventricular organs,
areas in the brain that lack a BBB. Being the vomiting center, it is
imperative that it lacks a BBB so that it can sample the systemic circulation.
Being in the medulla, it is the only circumventricular organ that is adjacent to the fourth
ventricle; all of the others are adjacent to the third. It is the only
paired circumventricular organ; all of the others are single and midline.
The other circumventricular organs are subfornical organ, organum vasculosum of the lamina terminalis,
median eminence, posterior pituitary gland, subcommissural organ, and pineal