Kjeld Møllgård

Department of Cellular and Molecular Medicine, KU
Title: "Sequential establishment of brain barrier interfaces during early human development"

Abstract: The developing brain is separated from the general internal environment of the embryo and fetus by a complex series of interfaces composed of morphological structures, cellular transporters and channels present in the cell membranes of these interfaces. All these components are often referred to colloquially as “the blood-brain barrier”. However, this is a misleading simplification especially as this term usually refers to morphological structures only. There are actually five barrier interfaces in the adult brain and a sixth that is present only during development.  In addition to various metabolic transporters these interfaces also contain influx/efflux pumps,  including ATP-binding cassette (ABC) transporters, that provide an important component of the barrier functions by either preventing entry of or expelling numerous molecules such as toxins, drugs and other xenobiotics. In this talk the sequential establishment of various spaces and interfaces during development, from the earliest time of neural tube closure when the brain anlage is fed by diffusion from the amniotic fluid, followed by establishment of the perineural vascular plexus (extrinsic diffusion of nutrients), and then angiogenesis and choroid plexus development leading to intrinsic vascularization and nutrition of the developing brain, is described based mainly on immunocytochemistry. The first complex barriers at the brain’s surface are particularly poorly defined in the literature, but with claudin-11 as a reliable marker for the arachnoid-barrier cell layer is has been possible to follow the establishment of the subarachnoid space and gain insight in the possible flow of the early CSF.