PROGESTERONE LEVELS IN THE RABBIT OVARIAN VEIN BLOOD THROUGHOUT PREGNANCY<sup>1</sup><sup>2</sup>

Mikhail, George R.; Noall, Matthew W.; Allen, Willard M.

doi:10.1210/endo-69-3-504

Cited by 62 publications

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“…Injection schedules were based on previous experience and on the literature, and were clearly a somewhat fortunate guess, in that pregnancy was often maintained in these ovariectomized animals. Since progesterone output from the rabbit ovary was known to be highest between days 15 and 20 of pregnancy (Mikhail et al 1961;Hilliard et al 1968), the daily dose of progesterone was increased from 1 mg in the early days of pregnancy to 6 mg on days 10-19, and decreased thereafter. The amount of oestradiol needed to interrupt pregnancy increases according to the stage of pregnancy (Greenwald 1957;Schofield 1962).…”

Section: Methodsmentioning

confidence: 99%

Hormonal Requirements for Implantation and Pregnancy in the Ovariectomized Rabbit

Kwun¹,

Emmens²

1974

Aust. Jnl. Of Bio. Sci.

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After induced ovulation and insemination on day 1, followed by ovariectomy on day 2, a schedule of 1 mg of progesterone in two injections in oil per day on days 2-4 inclusive followed by 2 or 3 mg per day on days 5-9 inclusive was found to induce implantation in the majority of ovariectomized rabbits. Implantation percentages (102 x total no. of implants on day 10 -;-no. of corpora lutea) in different groups of 8-11 rabbits varied between 24 and 61 %; sham-operated and vehicle-injected controls gave overall significantly higher percentages of 57-79%. The addition of 0·1--0·5 p-g of 3,17f3-oestradiol to experimental groups at various times during these procedures resulted in implantation percentages of 49-63 %, but did not consistently improve them.The only seemingly consistent effect of oestrogen was on implantation maintenance from day 10 onwards in does with surviving foetuses. These showed 5·1 implants/doe on day 10 and 2·8 foetuses/ doe on day 30 with progesterone alone, and 5·2 implants/doe on day 10 and 3·7 foetuses/doe on day 30 (a significant difference) with added oestradiol, as against 6·0 implants/doe and 3·8 foetuses/doe on days 10 and 30 respectively in control animals.Since the adrenal glands may contribute sufficient steroids, particularly oestrogens, to affect conclusions, rabbits both ovariectomized and adrenalectomized were subjected to similar tests in comparison with sham-operated controls. No effects of adrenalectomy or of added oestrogen were apparent, and the results were otherwise similar to those above.Overall, these findings demonstrate difficulties in producing consistent results and go far towards explaining the contradictory literature that has grown up on this subject.

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Section: Methodsmentioning

confidence: 99%

Hormonal Requirements for Implantation and Pregnancy in the Ovariectomized Rabbit

Kwun¹,

Emmens²

1974

Aust. Jnl. Of Bio. Sci.

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“…The high placental weights in the hormone-treated groups were at variance with the reverse trend in foetus weights. The maternal placenta normally reaches its maximum size by about the 16th day and regresses in late pregnancy (Hammond, 1935 (Mikhail, Noall & Allen, 1961).…”

Section: Introductionmentioning

confidence: 99%

Observations on Pregnancy in Intact Rabbits and in Ovariectomized Rabbits Treated With 17 hydroxyprogesterone Caproate

Pickworth¹,

Lamming²

1967

Reproduction

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“…The reproductive physiology of the human female differs in certain important aspects from that of the rabbit, a crucial factor being the source of progesterone during the last half of pregnancy. In the rabbit, the level of progesterone in the blood falls towards the end of pregnancy (Mikhail, Noall & Allen, 1961), and parturition may be delayed by the systemic admini¬ stration of progesterone (Portman, 1934; Csapo, 1955;Fuchs & Fuchs, 1958). On the other hand, in the human female, there is no detectable change in blood progesterone levels until after parturition (Short & Eton, 1959), and parturition is not delayed by progesterone administration (Pose & Fietitz, 1961).…”

Section: Introductionmentioning

confidence: 99%

Progesterone and the Accomplishment of Parturition in the Sheep

Bengtsson¹,

Schofield²

1963

Reproduction

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Summary. A flock of thirty ewes was observed through two pregnancies to determine whether parturition could be delayed by the systemic administration of gestagens. In the first season, the four treated groups received daily injections of 2-5 and 10 mg, 6a-methyl-17a-hydroxyprogesterone acetate (6-map) and 10 and 40 mg progesterone for 14 days starting 1 week before the expected date of delivery. The time and course of delivery appeared to be unaffected. The following season the dose levels were increased to 25 and 40 mg 6-map, and 80 and 160 mg progesterone. A high proportion of pregnancies was affected by this treatment. Some sheep delivered to schedule but most of the others had to be subjected to Caesarian section. The mortality of lambs delivered at term was higher than in the control group and in all the cases of delayed parturition the lambs died in utero. The foetal death was not considered to be due to post-maturity. The results are discussed and it is concluded tentatively that placental progesterone in the ewe is not replaceable by systemic progesterone.

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PROGESTERONE LEVELS IN THE RABBIT OVARIAN VEIN BLOOD THROUGHOUT PREGNANCY¹²

Cited by 62 publications

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Hormonal Requirements for Implantation and Pregnancy in the Ovariectomized Rabbit

Hormonal Requirements for Implantation and Pregnancy in the Ovariectomized Rabbit

Observations on Pregnancy in Intact Rabbits and in Ovariectomized Rabbits Treated With 17 hydroxyprogesterone Caproate

Progesterone and the Accomplishment of Parturition in the Sheep

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PROGESTERONE LEVELS IN THE RABBIT OVARIAN VEIN BLOOD THROUGHOUT PREGNANCY12

Cited by 62 publications

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Hormonal Requirements for Implantation and Pregnancy in the Ovariectomized Rabbit

Hormonal Requirements for Implantation and Pregnancy in the Ovariectomized Rabbit

Observations on Pregnancy in Intact Rabbits and in Ovariectomized Rabbits Treated With 17 hydroxyprogesterone Caproate

Progesterone and the Accomplishment of Parturition in the Sheep

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PROGESTERONE LEVELS IN THE RABBIT OVARIAN VEIN BLOOD THROUGHOUT PREGNANCY¹²