The role of the cheek pouch in effecting transplantation immunity in the hamster.

The cheek pouch of the hamster is alymphatic. Molecules, too large to penetrate the vascular endothelium, reach general circulation by slowly diffusing through the cheek pouch membrane to vessels found in the connective tissues in the neck and these vessels drain primarily into the superficial cervical node. The tissues of the cheek pouch membrane limit the diffusion of large particles and it is this "barrier" which explains, in part, the "privilege" conferred by the cheek pouch.