In rat, normal blood supply to the MCA tissue
field is via the main stem of the MCA originating
at the arterial circle of Willis (Brown,
1966; Greene, 1935; Zeman and Innes, 1963).
This study demonstrated dorsal ACA-MCA
anastomoses indicating the existence of alternate
cerebral channels for blood supply to the
MCA tissue field. Unlike in human data (vander
Eecken and Adams, 1953), there are more
but smaller diameter collaterals in rat. There is
no evidence for a decreased density of ACAMCA
junctions for one cortical region