How does formaldehyde affect cell permeability and why?
I think its effect on cell permeability is relatively mild, except that if the concentration is sufficiently high to be toxic to cells, that would cause them to increase their permeability as they die. This would be a very non-specific or indirect action. Formaldehyde is toxic because it cross-links proteins. It is commonly used in immunohistochemisty to “fix” tissues prior to further treatment with antibodies, and in this setting it is not very good at increasing permeability – you commonly have to add a detergent (like Triton X100) to allow antibodies access into cells.
