choroidea

Mesodermal tissue, continuous with that of the primitive falx cerebri, and carrying bloodvessels with it, spreads between the two layers of the invaginated fold and forms the rudiment of the tela choroidea; the margins of the tela become highly vascular and form the choroid plexuses which for some months almost completely fill the ventricular cavities; the tela at the same time invaginates the epithelial roof of the diencephalon to form the choroid plexuses of the third ventricle.

IX. Neurology. 2. Development of the Nervous System 1918