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. Author manuscript; available in PMC: 2014 Dec 1.
Published in final edited form as: Curr Opin Neurobiol. 2013 Jul 15;23(6):1057–1064. doi: 10.1016/j.conb.2013.06.006

Figure 2. Schematic representation of BBB development.

Figure 2

A) During early development, endothelial cell progenitors (brown) form a vascular plexus surrounding the developing neural tissue (blue).

B) Angiogenic sprouts, consisting of endothelial tip and stalk cells, invade the neural tissue under the influence of general angiogenic factors (VEGF) as well as CNS-specific angiogenic factors (Wnt). These initial sprouts recruit pericytes (green) and are observed to have ‘tight’ properties including tight junction proteins as well as Glut1 expression, as well as ‘leaky’ properties including high rates of transcytosis and expression of leukocyte adhesion molecules (LAMs) such as Icam1.

C) Over the next several days and weeks under the influence of pericyte-derived factors, neural derived factors and astrocyte derived factors, the endothelial cell tight junctions mature, the cells start to increase expression of efflux transporters and lower their transcytosis and expression of LAMs.