Steroid Hormone Production by Pig Blastocysts

Conjugated and unconjugated oestrogens in fetal and maternal fluids of the cow throughout 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).…”

Changes in the protein content of mouse uterine flushings during normal pregnancy and delayed implantation, and after ovariectomy and oestradiol administration

“…Within 12 h of oestradiol administration during dia¬ pause a quantitative increase in luminal protein concentration was observed in pregnant but not pseudopregnant mice and the increase was apparent several hours before the initiation of blastocyst attachment. It is therefore possible that the activated blastocysts induced a local increase in uterine secretory activity and capillary permeability through the release of, for example, steroids (Perry, Heap & Amoroso, 1973) or specific proteins (Jones, Heap & Perry, 1976).…”

Oestrogen production by blastocyst and early embryonic tissue of various species

“…In previous studies we reported biochemical evidence for the presence of aromatase in pig blastocysts (Perry, Heap & Amoroso, 1973; Burton, Gadsby, Saunders & Heap, 1979). Other enzymes of the steroid synthetic chain are also present in preimplantation pig embryos, and oestrogens are formed from pregnenolone and progesterone in vitro provided co-factors are added to the incubation medium (Gadsby, Burton, Heap .…”