Before revision: It is formed of capillaries with small pores that allow small molecules to pass through that have a molecular weight of less than 40,000 Daltons , but not larger macromolecules such as proteins.
After revision: It is formed of capillaries with small pores that allow small molecules to pass through that have a molecular weight of less than 40,000 daltons , but not larger macromolecules such as proteins.