Ek. Kristoffersen et E. Ulvestad, NITRIC-OXIDE SYNTHASE IN HUMAN PLACENTA, APMIS. Acta pathologica, microbiologica et immunologica Scandinavica, 102(7), 1994, pp. 509-513
Nitric oxide synthase is demonstrated immunohistochemically in the cyt
osol, on granules, and on syncytiotrophoblasts membranes. The enzyme i
s also detected on placental villous stroma cells, and on endothelial
cells. The histochemical staining method NADPH-diaphorase stains the s
yncytiotrophoblasts intensely, and stroma cells more weakly. Membranes
of syncytiotrophoblasts immobilized on nitrocellulose paper are also
stained by NADPH-diaphorase, and by antisera to nitric oxide synthase.
Oxidases of sex steroid synthesis do, however, influence placental tr
ophoblasts and there are discrepancies in the staining pattern of endo
thelial cells. Caution should therefore be exercised when using NADPH-
diaphorase as a staining method for nitric oxide synthase in placenta.