276 Vaccines and Autism
Luminal
membraneBlood HgEndothelial cellAbluminal
membraneLuminal
membraneBlood HgEndothelial cellTight junctionAstrocyteBasement
membrane
PericyteAstrocyteNeuronBrain
capillaryAbluminal
membrane
Tight junctionAstrocyteInflammatory cytokines
Mercury in vaccines/
Environmental
chemicals
Leaky BBBBasement
membrane
PericyteAstrocyteNeuronBrain
capillary(a)(b)Figure 9.1 The blood–brain barrier (BBB) is a highly selective semipermeable membrane
barrier that separates the circulating blood from the brain extracellular fluid in the CNS.
The BBB is formed by brain endothelial cells, which are connected by tight junctions.
(a) A normal BBB. (b) A leaky BBB, induced by inflammatory cytokines, particularly
interleukin 6 (IL‐6). (See insert for color representation of this figure.)