Evolutionary development of embryonic cerebrospinal fluid composition and regulation: an open research field with implications for brain development and function

Table 1 Chronology of the embryonic blood–brain barrier transport system formation

Morphological or physiological aspect	Embryonic day (E)
Morphological or physiological aspect	Chick	Rat
Closure of anterior neuropore/initial differentiation of eCSF protein content	E1.7−E2	E10.5−E11
Brain cavity becomes physiologically sealed	E3.5−E4	E12.4−E12.7
Transient embryonic blood–brain barrier starts to be physiologically functional	A bit before E4	A bit before E12.7

ISSN: 2045-8118