fuchsine (acid dye) and methylene blue (basic dye).

Substances of abuse include heroin and methylene dioxymethamphetamine (MDMA, or Ecstasy).

For example, the ligand methylene diphosphonate (MDP) can be preferentially taken up by bone.

Microscopic visualization of the encapsulated bacilli, usually in very large numbers, in a blood smear stained with polychrome methylene blue (McFadyean stain) is fully diagnostic, though culture of the organism is still the gold standard for diagnosis.

The main action of these aldehyde fixatives is to cross link amino groups in proteins through the formation of methylene bridges ( CH2 ), in the case of formaldehyde, or by a C5H10 cross links in the case of glutaraldehyde.