Electron microscopic demonstration of two types of mitochondria with different affinities for lead

Synopsis Incubation of glutaraldehyde-fixed, non-frozen tissue slices of mouse seminal vesicle, ventral prostate and small intestine in the media described by Hugon & Borgers (1966) and by Mayaharaet al. (1967) for the cytochemical demonstration of alkaline phosphatase resulted in the deposition of lead along smooth muscle mitochondrial membranes but not along epithelial mitochondrial membranes. Control studies using boiled tissues; media lacking substrate; inhibitors such as L-cysteine, EDTA,N-ethyl maleimide andp-chloromercuribenzoate; and tissues incubated in full media after fixation, embedding and sectioning, showed that the reaction in muscle mitochondria was non-enzymatic. It was concluded that the phospholipid component of muscle mitochondrial membranes differed from that of epithelial mitochondrial membranes.