title: The permeability to exogenous protein of the wall of the superior sagittal sinus of the cat.
abstract: The permeability of the wall of the superior sagittal sinus of the cat has been studied using horseradish peroxidase (HRP) as an exogenously applied tracer. Cats were given intracisternal or intravascular injections of HRP before being perfused transcardially for examination of sinus tissues with the electron microscope. Tissues were processed with diaminobenzidine to reveal peroxidase activity. A diffusion barrier to the protein tracer was seen to occur at the level of the arachnoid mater. When injections of HRP were made into the cisterna magna, the protein was able to course through the subarachnoid space surrounding the sinus, and sequestration of the tracer was seen in deep cell layers of the arachnoid mater. However, a series of zonulae occludentes at more apical levels of the arachnoid prevented the tracer from penetrating intercellularly to the level of the dura mater. Conversely, when HRP was given intravascularly, the protein penetrated intercellular spaces of the dura mater and apical levels of the arachnoid mater, stopping at the level of the zonulae occludentes of the arachnoid. This barrier layer appears to be continuous with the arachnoid barrier layer which prevents diffusion of large molecules through the arachnoid mater over the brain convexities.
mesh_terms: D000818:Animals; D001099:Arachnoid / Q000033:anatomy & histology; D002196:Capillaries / Q000033:anatomy & histology; D002415:Cats / Q000378:metabolism*; D003392:Cranial Sinuses / Q000033:anatomy & histology / Q000378:metabolism*; D005260:Female; D006735:Horseradish Peroxidase; D008297:Male; D011506:Proteins / Q000378:metabolism*
chemical_list: D011506:Proteins; D006735:Horseradish Peroxidase