Table 1.

Characteristics of the intramural cells found within the walls of intracerebral arterioles and venules, as seen in transverse sections though the vessels with transmission electron microscopy.

Ultrastructural features	Arteriole	Venule
Complete/incomplete layer around vessel	Always complete	Often incomplete
Intramural cell shape	Square/rectangular, “block like”	Flattened/spindle-like
Number of intramural cell layers	Most commonly 1, occasionally 2, rarely 3	1 Layer, occasionally cells overlap
Caveolae (flask shaped invaginations of the cell membrane)	Present	Rare
Electron dense myosin bands (part of contractile apparatus)	Present	Rare