The localisation of diaphorase was visualised by light microscopy using the
dye nitro blue tetrazolium and NADPH as substrates. Under appropriate cond
itions, diaphorase reduces this dye to a dark blue insoluble formazan. The
enzyme was located at very low activity in many tissues and glandular struc
tures of the deer, but at very much higher activity in sebaceous glands in
the dermal velvet of the antler and skin, and in additional sebaceous gland
-related structures in the ear canal, prepuce and tail (scent) gland. Withi
n sebaceous glands, activity was greatest in the outermost layers of the ac
ini, but decreased as the cells progressed and differentiated centripetally
. There was little or no difference between the staining observed when NADH
was used as a substrate, compared to NADPH. There was generalised staining
(usually light) for glucose-6-phosphate dehydrogenase, lactate dehydrogena
se, and glycerol-3-phosphate dehydrogenase. However, this staining was not
specifically localised to sebaceous glands and related structures, showing
that the observed activity in these structures was due to a diaphorase that
was distinct from any of the dehydrogenase activities tested. The possible
role of diaphorase in sebaceous development and secretion is discussed. (C
) 1999 Elsevier Science Inc. All rights reserved.