Effects of female sex hormones in whole embryo culture

Much work has been done in vivo on the effects of sex steroids on the developing foetus. Many genital anomalies have been reported; defects of other organ systems have been suggested. Synthetic oestrogens are considered to be developmental toxicants in vivo, while natural oestrogens are thought to present little or no risk. A small selection of hormones (17β-oestradiol, 17α-ethynyloestradiol, diethylstilboestrol and progesterone) was tested using the rat whole embryo culture technique to see whether this difference could also be confirmed in vitro. Dysmorphogenic embryotoxic effects were evident with both natural and synthetic oestrogens, but at much higher concentrations than would be expected to circulate in humans after therapeutic use.