IMMUNOLOGY

Detailed explanation-1: -Blood vessels, especially those of microvessels, serve as a semipermeable barrier between blood contents and the tissue, which is much more permeable than epithelial systems.

Detailed explanation-2: -The glomerular capillary is relatively impermeable to most serum proteins. This impermeability that leads to virtual exclusion of proteins like albumen from the glomerular filtrate but permits complete permeation by inulin is thought to be related in part to the molecular dimensions of the protein.