Neuroanatomy

Perivascular spaces, also known as Virchow-Robin spaces are fluid-filled spaces in the brain that surrounds small arterioles, capillaries and venules in the brain.
Biological Psychiatry https://doi.org/10.1016/j.biopsych.2021.06.025

The primary intraparenchymal meningioma of the
frontal lobe (A) with no apparent dural attachment. The
presumption is that arachnoid cells present in the pia mater
migrate together with penetrating blood vessels during
brain development (B).
World Neurosurgery, Sept. 2021
https://doi.org/10.1016/j.wneu.2021.06.139