The Effects of Estrogens, Progestagens, and Relaxin in Pregnant and Nonpregnant Laboratory Rodents

Kroc, Robert L.; Steinetz, Bernard G.; Beach, V. L.

doi:10.1111/j.1749-6632.1959.tb44603.x

Cited by 163 publications

(76 citation statements)

References 33 publications

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“…Oestrogens increased cervical weight and inner circumference in the non-pregnant rat but produced only small increases in cervical extensibility (Kroc et al, 1959;Cufien & Harkness, 1960;Zarrow & Yochim, 1961). The changes in the cervix described by Kroc et al (1959) and arrow & Yochim (1961) are probably mainly reflections of increased tissue mass rather than greater extensibility. Oestradiol administered in large doses to women at term produced some cervical softening as judged clinically (Pinto, Fisch, Schwarcz & Montiori, 1964;Gordon & Calder, 1977).…”

Section: Discussionmentioning

confidence: 99%

“…Progesterone is able to increase slightly cervical weight and inner circumference above that of oestrogen-treated rats but does not increase extensibility (Kroc et al, 1959;Cufien & Harkness, 1960;Zarrow & Yochim, 1961). As peripheral plasma concentrations of progesterone decline in the late pregnant rat from about Day 17 or 18 (Csapo & Wiest, 1969;Buckle & Nathanielsz, 1975) increased cervical extensibility could be a direct consequence of progesterone withdrawal.…”

Section: Discussionmentioning

confidence: 99%

“…Uyldert & De Vaal (1947) showed that the inner circumference of the cervix still increased during pregnancy in rats whose uterine horns were surgically separated from the cervix, suggesting hormonal control of this change. Oestrogens alone and in combination with progesterone and/or relaxin can increase cervical size and produce small increases in cervical extensibility in non-pregnant and mid-pregnant, ovariectomized rats (Kroc, Steinetz & Beach, 1959;Cullen & Harkness, 1960;Zarrow & Yochim, 1961). Cervical dilatation in the pre-term sheep following fetal dexamethasone infusions was said to be inhibited by progesterone injections (Liggins, 1973) although this has not been supported by more quantitative measurements (Stys, Clewell & Meschia, 1978).…”

Section: Introductionmentioning

confidence: 98%

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The effects of oestradiol benzoate, progesterone, relaxin and ovariectomy on cervical extensibility in the late pregnant rat

Hollingsworth¹,

Isherwood²,

Foster³

1979

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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The effects of oestradiol benzoate, progesterone, relaxin and ovariectomy on cervical extensibility in the late pregnant rat

Hollingsworth¹,

Isherwood²,

Foster³

1979

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“…Relaxin (Warner-Chilcott preparation 'Releasin' W1164A Lot 53) in 0-1 ml. of beeswax and arachis oil [Kroc, Steinetz and Beach, 1959] [Harding, 1963]. Calculation from the hydroxyproline content of this would give about 5 per cent lower figures than with the factor 7 46.…”

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confidence: 99%

Collagen Formation and Changes in Cell Population in the Rat's Uterus After Distension With Wax

Cullen

Harkness

1968

Exp Physiol

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Injection, through the cervical canal, of wax into the lumen of the uterine horn of spayed rats treated with a mixture of ostradiol-17 ,B, progesterone and relaxin, produced an increase in the total collagen content of the horn (estimated by determination of hydroxyproline). This occurred as a later phenomenon in a general growth process, accompanied by increase in the weight of the horn and cell division.Counts of the proportion of nuclei in mitosis after a single injection of wax showed increase within 24 hr., subsiding in 4 days. Estimates of total numbers of nuclei in the horn were also made in sections of fixed material from undistended and distended horns 4 Harkness, 1956 b]. These observations indicate that the mechanical effect of distension is a major factor in stimulating collagen formation, but do not exclude the possibility of a local hormonal stimulus arising from the fcetus. It therefore seemed of interest to investigate the effect of distension directly. Wax was introduced through the cervical canal and was found to induce collagen formation associated with a general growth response, involving cell division in all layers of the uterine wall.A preliminary account of this work has already been published [Cullen and Harkness, 1959].MATERIALS AND METHODS Animals. Virgin albino rats of the local strain, about 3 months old, were spayed by the dorsal route 2-4 weeks before experiments. Animals were selected for inclusion in the different experimental groups by reference to a table of random numbers.Treatment. In preliminary experiments on normal animals, it was found that material placed in the uterus was frequently expelled. As it was undesirable to prevent this by physical obstruction, we attempted to simulate the hormonal conditions in pregnancy when the uterus does not expel its contents. We used the following treatment which had previously been found to bring the cervix into a state resembling that of the second half of pregnancy [Cullen and Harkness, 1960]: Day 0. CEstradiol cyclopentyl propionate (Depo-estradiol, Upjohn) 10 ,ug. in 0*1 ml. olive oil subcutaneously.

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“…These results may well indicate that the antifertility effects of LCI. 33,828 Kroc, Steinetz & Beach (1959) that pregnancy in rats ovariectomized on Day 15 of pregnancy can be maximally maintained by daily subcutaneous injections of 1-0 µg oestradiol-17-ß combined with either 1-0 or 2-0 mg progesterone. Yochim & Zarrow (1961), however, found that after ovariectomy of rats on Day 12, pregnancy could be maintained by subcutaneous administration of oestradiol and progesterone in ratios varying from 1 : 5000 to 1 : 50,000, provided that at least 1-0 mg progesterone was injected daily into each rat.…”

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confidence: 99%

Effects of 1- -Methylallylthiocarbamoyl-2-Methylthiocarbamoylhydrazine (I.C.I. 33,828) on Early Pregnancy in the Rat

Harper¹

1964

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The Effects of Estrogens, Progestagens, and Relaxin in Pregnant and Nonpregnant Laboratory Rodents

Cited by 163 publications

References 33 publications

The effects of oestradiol benzoate, progesterone, relaxin and ovariectomy on cervical extensibility in the late pregnant rat

The effects of oestradiol benzoate, progesterone, relaxin and ovariectomy on cervical extensibility in the late pregnant rat

Collagen Formation and Changes in Cell Population in the Rat's Uterus After Distension With Wax

Effects of 1- -Methylallylthiocarbamoyl-2-Methylthiocarbamoylhydrazine (I.C.I. 33,828) on Early Pregnancy in the Rat

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