Editing Blood–brain barrier (section)

===Specialized permeable zones===
The border zones between brain tissue "behind" the blood–brain barrier and zones "open" to blood signals in certain CVOs contain specialized hybrid capillaries that are leakier than typical brain capillaries, but not as permeable as CVO capillaries. Such zones exist at the border of the area postrema—[[nucleus tractus solitarii]] (NTS),<ref name="nts">{{cite journal | vauthors = Gross PM, Wall KM, Pang JJ, Shaver SW, Wainman DS | title = Microvascular specializations promoting rapid interstitial solute dispersion in nucleus tractus solitarius | journal = The American Journal of Physiology | volume = 259 | issue = 6 Pt 2 | pages = R1131-8 | date = December 1990 | pmid = 2260724 | doi = 10.1152/ajpregu.1990.259.6.R1131 }}</ref> and median eminence—[[hypothalamus|hypothalamic]] [[arcuate nucleus]].<ref name=Design/><ref name="ctr">{{cite journal | vauthors = Shaver SW, Pang JJ, Wainman DS, Wall KM, Gross PM | s2cid = 27789146 | title = Morphology and function of capillary networks in subregions of the rat tuber cinereum | journal = Cell and Tissue Research | volume = 267 | issue = 3 | pages = 437–48 | date = March 1992 | pmid = 1571958 | doi = 10.1007/BF00319366 }}</ref> These zones appear to function as rapid transit regions for brain structures involved in diverse neural circuits—like the NTS and arcuate nucleus—to receive blood signals which are then transmitted into neural output.<ref name=Design/><ref name=nts/> The permeable capillary zone shared between the median eminence and hypothalamic arcuate nucleus is augmented by wide pericapillary spaces, facilitating bidirectional flow of solutes between the two structures, and indicating that the median eminence is not only a secretory organ, but may also be a sensory organ.<ref name=Design/><ref name=ctr/>