Localization and distribution of unconjugated steroid hormones in normal placenta at term.

The localization and distribution of unconjugated oestrone, oestradiol-17 beta, oestriol and progesterone were studied in normal term placentae, using subcellular fractionation and indirect immunofluorescence techniques. Radioimmunoassay of these steroids in each subcellular fraction showed that they were detectable mainly in the cytosol fraction. The efficiency of fixatives for retaining steroids in placental tissue during immunohistochemical procedures was studied in order to validate the present experimental techniques. As compared with other fixatives, glutaraldehyde solution produced minimal leakage of steroid hormones from placental tissue. Using an indirect immunofluorescence technique oestrone, oestriol and progesterone were detectable in the cytoplasm of villous syncytiotrophoblast of fixed term placentae.