Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, U.K.
M. J. N. C. Keirse, B. R. Hicks and A. C. Turnbull
M. J. N. C. Keirse, M. D. Mitchell and A. P. F. Flint
Summary. 15-Hydroxyprostaglandin dehydrogenase (PGDH) was measured in vitro in myometrium and maternal cotyledons from 6 sheep and in fetal cotyledons from 3 sheep before and after parturition. Maternal cotyledons contained more PGDH than fetal cotyledons or myometrium. At parturition, PGDH activity decreased in myometrium but increased in fetal and maternal placental tissue. The enzymatic activity observed in vitro did not result in a large, consistent release of prostaglandin F metabolites into the utero-ovarian vein in vivo, and such activity may have a strictly localized effect in ovine parturition.
R. M. F. van der Weiden, L. J. Wisse, F. M. Helmerhorst, M. J. N. C. Keirse and R. E. Poelmann
The immunohistochemical and ultrastructural localization of prostaglandin H synthase (PGH synthase) was studied in the Albino Swiss CF-1 mouse at different stages of embryonic development (two-cell stage, four–eight cell stage, morula and blastocyst). Flushed embryos and sections of uteri and oviducts containing embryos were treated with a mouse IgG monoclonal anti-PGH synthase antibody. The second antibody (rabbit anti-mouse) was conjugated with peroxidase or fluorescein isothiocyanate for light microscopy, fluorescence microscopy and confocal scanning. For reflection contrast microscopy and transmission electron microscopy a second antibody, goat anti-mouse, was conjugated with ultrasmall gold particles. Controls without anti-PGH synthase were used concurrently. All embryos demonstrated PGH synthase reactivity. Immunostaining appeared to be more intense at the two-cell stage, four–eight cell stage embryos and morulae than in blastocysts. Further examination indicated an intracytoplasmic location for PGH synthase, which was confirmed by stereoscopic photographs made during confocal scanning microscopy and by the immunostaining patterns observed with reflection contrast microscopy and transmission electron microscopy. Transmission electron microscopy immunostaining patterns support the localization of PGH synthase in the endoplasmic reticulum. This is the first demonstration of the ultrastructural localization of PGH synthase in the mouse embryo. Its presence before the apposition with the endometrial epithelium supports the hypothesis that arachidonic acid metabolism via the PGH synthase pathway may be crucial for implantation.