Effect on Pregnancy in the Pig after Killing Embryos or Fetuses in One Uterine Horn in Early Gestation

Dhindsa, Dharam S.; Dziuk, P. J.

doi:10.2527/jas1968.271122x

Cited by 97 publications

(44 citation statements)

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“…The results from studies in vivo (Bazer et al, 1982) showed that peripheral progesterone in the blood decreased to 10-25 ng ml"1 on days 20-30 of pregnancy, whereas prostaglandin concentrations in the utero-ovarian vein were very low and similar to those in hysterectomized pigs (King, 1990). The extent of the initiation of a transient period of luteo¬ lysis in early pregnancy would not be expected to mimic fully the changes seen during the oestrous cycle due to: (i) the considerably smaller number of PGF2(1 receptors on the corpus luteum of pregnant compared with nonpregnant pigs (Gadsby et al, 1990), (ii) the lack of luteolytic factors from the uterus, as it is well documented that during pregnancy uterine PGF2a is sequestered in the uterus (Bazer et al, 1982) and (iii) it is likely that the corpus luteum would already have received luteotrophic support of embryonic (Dhindsa & Dziuk, 1968;Ball & Day, 1979; Van der Meulen et al, 1988) or pituitary (Brinkley et al, 1964, authors' unpublished observations) origin.…”

Section: Discussionmentioning

confidence: 99%

Effect of prostaglandins on luteal function during early pregnancy in pigs

Więsak

Hunter²,

Foxcroft³

1992

Reproduction

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Summary. Luteal cells were obtained by digestion of luteal tissue of cyclic (day 12) and early pregnant (days 12, 20 and 30) pigs. Suspensions of the dispersed luteal cells (5 x 104 cells ml \m=-\1) were incubated for 2 h in minimum essential medium (MEM) alone (control) and MEM with different concentrations of prostaglandin FF2\ g=a\(PGF2\g=a\) and PGE2 (0\m=.\01,0\m=.\1,1, 10, 100 and 1000 ng ml \m=-\1) and luteinizing hormone (LH) 100 and 1000 ng ml\m=-\1, or with combinations of LH+ PGF2\g=a\and LH + PGE2. Net progesterone production was measured in the incubation media by direct radioimmunoassay.The overall response pattern of the luteal cells to exogenous hormones on day 12 of the oestrous cycle and pregnancy differed (P < 0\m=.\5) from treatment on day 20 and 30 of pregnancy. In general progesterone production was higher (P < 0\m=.\5) and the response to PGF2\g=a\ and PGE2 treatment was most obvious on day 12 of the oestrous cycle and pregnancy. Overall, PGF2\g=a\ stimulated progesterone production in a dosedependent manner (P < 0\m=.\05). The response to PGE2 was of a quadratic nature (P < 0\m=.\05) in which the lowest and the highest doses of PGE2 were associated with a greater production of progesterone than were the intermediate doses. Treatment of luteal cells with PGF2\g=a\ + LH or PGE2 + LH caused overall inhibition (P < 0\m=.\05) of progesterone production compared with treatment with each hormone alone. This interaction was not affected by the dose of LH used.These findings indicate that PGF2\g=a\ and PGE2 are involved in the autocrine control of corpus luteum function.

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Section: Discussionmentioning

confidence: 99%

Effect of prostaglandins on luteal function during early pregnancy in pigs

Więsak

Hunter²,

Foxcroft³

1992

Reproduction

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“…Further work has shown that aromatase is detectable by the time of maternal recognition of pregnancy , an event that begins on about Day 12 post coitum (p.c.) (Dhindsa & Dziuk, 1968), and it has been suggested that oestrogens of trophoblast origin may be the embryonic signal which initiates this event . In addition, trophoblast oestrogens have been implicated in the process of implantation since in certain animals implantation occurs after ovariectomy when the operation is performed in early pregnancy and progesterone alone is administered (Dickmann, Dey & Sen Gupta, 1976).…”

Section: Introductionmentioning

confidence: 99%

Oestrogen production by blastocyst and early embryonic tissue of various species

Gadsby¹,

Heap²,

Burton³

1980

Reproduction

138

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“…The embryonic signal which initiates luteal maintenance occurs on about Day 12 after mating in the sow (Dhindsa & Dziuk, 1968) and is associated temporally with a transient increase in blood flow to the gravid uterine horns (Ford & Christenson, 1979). The pig embryo develops the capacity to synthesize oestrogens in vitro by Day 12 of gestation (Perry, Heap, Burton & Gadsby, 1976).…”

Section: Introductionmentioning

confidence: 99%