Production of thromboxane B2 by the intra-uterine tissues from late pregnant Rhesus monkeys (Macaca mulatta) in vitro.

The rates of production of thromboxane B2 in vitro by intra-uterine tissues obtained from late pregnant monkeys by Caesarean section have been determined. The general quantitative order of rates of production was decidua basalis = decidua parietalis greater than placenta greater than chorion greater than amnion = myometrium. Myometrial production of thromboxane B2 was greater at term than during late pregnancy; no other tissue showed a significant trend with advancing gestation. These data demonstrate that the production of thromboxane B2 by intra-uterine tissues from late pregnant monkeys is both qualitatively and quantitatively different from the production of prostaglandins described previously. It is suggested that prostaglandins rather than thromboxanes are more intimately involved in the onset of labour in the rhesus monkey.