Differential staining of dead and dying embryonic cells with a simple new technique.

A new staining technique with toluidine blue and safranin is described which yields satisfactory results in histological sections of chick embryo tissue fixed in a mixture of glutaraldehyde and formaldehyde and embedded in Spurr's resin. In zones of embryonic cell death, this technique allows the blue-staining of dying cell pyknotic nuclei to be clearly distinguished from red-staining healthy cells. The possible factors underlying this differential staining of pyknotic nuclei are discussed.