The appearance of oestrone sulphate in the peripheral plasma of the pig early in pregnancy

Conjugated and unconjugated oestrogens in fetal and maternal fluids of the cow throughout pregnancy

“…Similar observations have been made for the chorioallantoic fluid of the sheep (Carnegie & Robertson, 1978) and the peripheral plasma of the pregnant sow (Robertson & King, 1974; Robertson, King & Dyck, 1978). As it is well established that steroid hormones influence the development and maturation of the fetus during intrauterine life (Jost, 1969(Jost, , 1970 Gorski, 1971) and, later, the induction of parturition (Liggins, 1969), it was considered expedient to extend our investigations on the concentrations of oestrogens in fetal and maternal fluids of the pregnant cow to cover the complete period of pregnancy.…”

“…Gadsby, Burton, Heap & Perry (1976) failed to obtain evidence for oestrogen synthesis in vitro by either tissues or membranes of the early bovine or ovine conceptus although Attal (1969) (Carnegie & Robertson, 1978) and in the peripheral plasma of the pregnant sow (Robertson & King, 1974;Robertson et al, 1978) (Carnegie & Robertson, 1978). This drop in the concentration of the oestrogen sulpho-conjugates late in pregnancy is in keeping with an observed fall in the concentration of the unconjugated oestrogens in the blood of fetal calves during the 8th month (Challis et al, 1974) and of the sulpho-conjugates in fetal ovine blood (Wong, Cox, Durrie & Thorburn, 1972;Findlay & Seamark, 1973 (Perry, Heap & Amoroso, 1973) and oestrogens of embryonic origin have been detected in the maternal peripheral plasma by Day 17 (Robertson & King, 1974;Robertson et al, 1978), suggests that the first appearance of oestrogens in the conceptus of the cow occurs much later in relation to the start of attachment to the maternal uterus. The cow may therefore be more like the ewe in which evidence for oestrogen synthesis by the conceptus was first found around Day 31 (Carnegie & Robertson, 1978).…”

Effect of oestrogen antisera early in gestation on pregnancy maintenance in the pig

“…Goldenberg, Bridson & Köhler (1972) found that oestrogens stimulated progesterone synthesis by porcine granulosa cells in culture, which suggests that the effect of oestrogens on the maintenance of the corpora lutea in the pig is mediated, at least in part, by a direct action on the luteal tissue. These observations, together with those of Perry et al (1973,1976) that the Day 12 pig blastocyst tissue synthesizes oestrogens in vitro, and those of Robertson & King (1974) and Robertson et al (1978) that oestrone sulphate arising from the uterus can be detected in maternal plasma by Day 16-17, suggested that embryonic oestrogens or their sulphoconjugates may be luteotrophic in the pig.…”

“…The observation that pig blastocysts are capable of synthesizing oestrogens in vitro from Day 12 of gestation (Perry, Heap & Amoroso, 1973; Perry, Heap, Burton & Gadsby, 1976) and the detection of this oestrogen in plasma as oestrone sulphate as early as Days 16-17 of pregnancy (Robertson & King, 1974;Robertson, King & Dyck, 1978) have led to the hypothesis that oestrogens of embryonic origin or their sulphates may act either as an embryonic signal for the maternal recognition of pregnancy by exerting a luteotrophic effect on the corpora lutea or may be involved in the initiation of placental attachment.…”

Direct estimation of oestrone sulphate in sow serum for a rapid pregnancy diagnosis test

“…Previous work on pigs had shown a marked increase in serum oestrone sulphate concentrations during early pregnancy, and the evidence indicated that this might form the basis of an early pregnancy diagnosis test (Robertson & King, 1974;Robertson, King & Dyck, 1978; Hattersley, Drane, Matthews, Wrathall & Saba, 1980 Phosphate-buffered saline pH 7-0 (PBS). This consisted of 0-05 M-phosphate, 0-9% (w/v) sodium chloride, 0-05% gelatin and 0-1% sodium azide.…”