Uterine blood flow of cows during the oestrous cycle and early pregnancy: effect of the conceptus on the uterine blood supply

Ford, Stephen P.; Chenault, J.R.; Echternkamp, S. E.

doi:10.1530/jrf.0.0560053

Cited by 120 publications

(80 citation statements)

References 27 publications

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“…The inhibition of spontaneous myometrial activity in this peri-implantation period resembled the classic progesterone 'block' described by Csapo (1956Csapo ( , 1977 . Greiss & Anderson (1970a) Ford, Chenault & Echternkamp, 1979; pigs: Ford & Christenson, 1979), particularly in the uterine horn occupied by a conceptus, and these increases have been correlated with oestrogen production by the early embryo. Short-term changes in uterine blood flow would not have been detected readily in the present study, but the flow rates in pregnant (4-fold) and non-pregnant (0-5 -fold) animals were considerably higher than the values obtained by Greiss & Anderson (1970a) in ewes with chronically implanted flow probes and warrant further consideration.…”

Section: Discussionmentioning

confidence: 99%

Uterine blood flow, myometrial activity and their response to adenosine during the peri-implantation period in sheep

Fleet¹,

Heap²

1982

Reproduction

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Summary. Uterine blood flow and myometrial activity were measured simultaneously in anaesthetized sheep 15 days after a sterile (non-pregnant group) or fertile (pregnant) mating. During the peri-implantation period uterine blood flow was similar in both groups of animals, but spontaneous myometrial activity was greatly reduced in pregnant ewes. This 'block' of myometrial activity was associated with circulating levels of progesterone which were significantly higher (2\m=.\8\ m=+-\0\m=.\8ng/ml, mean \m=+-\ s.e.m.) than those in non-pregnant animals (0\m=.\4 \m=+-\0\m=.\3 ng/ml). Adenosine injected into the uterine artery produced uterine vasodilatation in both groups, but the log dose\p=n-\response was significantly less in pregnant than in non-pregnant animals (P < 0\m=.\001).Myometrial activity was stimulated by adenosine, particularly in the pregnant group (P < 0\m=.\001

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Section: Discussionmentioning

confidence: 99%

Uterine blood flow, myometrial activity and their response to adenosine during the peri-implantation period in sheep

Fleet¹,

Heap²

1982

Reproduction

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“…Total conjugated oestrogens in the plasma of gilts increase between 70 and 110 days of gestation [5,26], and it is well established that through dilatation of the uterine blood vessels, oestrogens have a positive effect on UBF [6,14,23]. Increase of UBF at day 12-13 and before day 30 of gestation was described in relation to the presence of embryos in sows [24] and cows [25]. An increase of UBF during later stages has been described in many species.…”

Section: Variation Of Ubf With Pregnancy Stagementioning

confidence: 99%

Uterine blood flow in sows: effects of pregnancy stage and litter size

Père

Etienne

2000

Reprod. Nutr. Dev.

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-Female pigs were assigned to three groups at 94 days of age: a control group (CTR), a group undergoing the ligation and severing of the left oviduct (LIG), and a group undergoing right hysteroovariectomy (HHO). They were inseminated at 307 days of age. At 35 days of pregnancy, an ultrasonic transit time flow probe was implanted around the middle artery of one uterine horn in 33 sows and uterine blood flow was measured during thirteen 24-h periods between 44 and 111 days. Despite large differences in ovulation rate per uterine horn (4.8, 8.3 and 16.9 in the LIG, CTR and HHO groups, respectively), variation of litter size was considerably reduced with advancement of pregnancy (3.0, 6.6 and 10.8 foetuses per uterine horn at 35 days, and 3.0, 5.8 and 4.9 at 112 days (slaughter), respectively). Uterine blood flow increased linearly during pregnancy. It was lower in the LIG sows (0.82 to 1.74 L . min -1. horn -1 from 44 to 111 days) than in the CTR and HHO sows (1.22 to 2.84 and 1.09 to 2.63 L . min -1. horn -1 , respectively). It was more closely related to litter weight than to litter size and amounted to 0.42 L . min -1. kg foetus -1 at 111 days. Uterine blood flow per foetus decreased when litter size increased. It increased from 0.31 to 0.72, 0.26 to 0.60 and 0.20 to 0.43 L . min -1. foetus -1 from 44 to 111 days when there were 2 to 3, 4 to 5, and 6 to 8 foetuses in the uterine horn, respectively. This explains why piglets from large litters are lighter at birth.

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“…It has been proposed that a mechanism by which blastocyst oestrogen production may prolong luteal function in early pregnancy may involve a redirection of uterine prostaglandin (PG) secretion away from uterine venous blood towards the uterine lumen, thereby protecting the corpus luteum from the luteolytic effect of PGF-2a . In the cow, maternal recognition of pregnancy occurs about Day 16 (Betteridge, Eaglesome, Randall, Mitchell & Sugden, 1978) and this coincides with the formation of oestradiol-17ß from labelled androstenedione by some conceptuses, beginning on Day 15 (Eley, Thatcher, Bazer & Fields, 1979), and with the local increase in uterine blood flow (Ford et al, 1979) Greiss & Anderson (1970) also suggest an increase in uterine blood flow to the gravid horn during the preimplantation period consistent with uterine vasodilatation associated with local oestrogen administration (Greiss & Miller, 1971 (Allen, 1979), or luteotrophic (Berg & Ginther, 1978) as in the sow. The association of superficial implantation and pronounced aromatase activity in the preimplantation trophoblast of sows and mares raises the possibility that these events are related; however, in the mare endometrial invasion by highly specialized trophoblast cells occurs between Days 36 and 3Bp.c.…”

Section: Introductionmentioning

confidence: 98%

Oestrogen production by blastocyst and early embryonic tissue of various species

Gadsby¹,

Heap²,

Burton³

1980

Reproduction

138

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Uterine blood flow of cows during the oestrous cycle and early pregnancy: effect of the conceptus on the uterine blood supply

Cited by 120 publications

References 27 publications

Uterine blood flow, myometrial activity and their response to adenosine during the peri-implantation period in sheep

Uterine blood flow, myometrial activity and their response to adenosine during the peri-implantation period in sheep

Uterine blood flow in sows: effects of pregnancy stage and litter size

Oestrogen production by blastocyst and early embryonic tissue of various species

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