Influence of One or Two Ovaries on Ovulation and Ovarian Weight in the Hypophysectomized Rat

Greenwald, Gilbert S.

doi:10.1210/endo-82-3-591

Cited by 16 publications

(9 citation statements)

References 4 publications

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“…Therefore the ovarian compensatory hypertrophy obtained after 7 days is not significant (P <0 '1), significant after 15 days (P<O'OI) and highly significant thereafter (P<O·OOI). These results agree with those of Greenwald (1968) and Peppler (1972), wherein the significant compensatory hypertrophy is obtained with an increase in the time of exposure of the ovary to the constant gonadotrophic levels. The maximum ovarian hypertrophy is observed by 20 days after hemispaying.…”

Section: 4 Estrous Cyclesupporting

confidence: 91%

“…However, this contention is questioned as there is an increase in the gonadotrophin output, due to decrease in the circulating estrogen after hemispaying which is responsible for the ovarian compensatory hypertrophy (Grady and Greenwald 1968 ;Benson et al 1969;Walshen 1970Walshen , 1972Howland and Skinner 1973). But according to Greenwald (1968) and Peppler (1972) the mechanism of ovarian hypertrophy involves not only an increase in the output of pituitary gonadotrophins, but also the time of exposure to the available gonadotrophins.…”

Section: 4 Estrous Cyclementioning

confidence: 99%

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Durational effects of hemispaying on ovarian hypertrophy and estrous cycle in albino rats

Patil

Rao²

1982

Proc Ani Sci

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OVarian hypertrophy is studied by hernispayins the rats for 7, 15, 20, 25 and 30 days. The compensatory hypertrophy of the ovary is calculated in relation to their respective sham operated controls. The maximum hypertrophy is observed 20 days after hemispaying, as indicated by ovarian weight and its histological observations. Thereafter the hypertrophic response though significant, decreases gradually, indicating that Once the circulating estrogen seer.ted by the hypertrophied ovary COmes to preoperative level, the pituitary gonadotrophin level also falls down. The hemispaying has no significant effect eithc! on the duration or number of estrous cycle.

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Section: 4 Estrous Cyclesupporting

confidence: 91%

Section: 4 Estrous Cyclementioning

confidence: 99%

Durational effects of hemispaying on ovarian hypertrophy and estrous cycle in albino rats

Patil

Rao²

1982

Proc Ani Sci

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“…The present experiments using progesterone treatment to nulUfy any feedback mechanism support earher attempts, using hypophysectomy, to show that ovulatory compensation arises through a feedback mechanism rather than a consumption mechanism. In three experiments on hypophysectomized rats, PMSG and hCG produced no more ovarian response (weight, follicular development or ovulations) in unUateraUy ovariectomized rats than in those with intact ovaries (Selye, 1940;Greenwald, 1968;Welschen, 1972). The hypophysectomy experiments alone are not conclusive since hypophysectomy reduces ovarian sensitivity to PMSG (Wüliams, 1944) and one cannot judge whether the doses of PMSG were at the critical levels required to show ovulatory compensation (Zarrow, Sundaram & Stob, 1965;McLaren, 1966).…”

Section: Discussionmentioning

confidence: 87%

Can reduced consumption of gonadotrophins account for ovarian compensation in unilaterally ovariectomized, immature mice injected with gonadotrophins?

Gibson¹,

Ingram²,

Lee³

1979

Reproduction

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The effect of unilateral ovariectomy on ovulation rates in immature mice was studied. Ovulations were induced by injecting PMSG and hCG and their number was determined by counting tubal oocytes. A 2--3-fold increase in number of ovulations per ovary was observed after unilateral ovariectomy, and daily injections of progesterone abolished this ovulatory compensation. No significant increase in serum concentrations of immunoreactive FSH and LH was observed at 4, 8, 32 and 51 h after unilateral ovariectomy. Progesterone treatment lowered FSH levels at all times, while LH was unaffected. In intact mice, ovarian sensitivity to PMSG and hCG was not substantially affected by progesterone. Ovulatory compensation in immature gonadotrophin-injected mice appears to arise through a negative feedback mechanism and transiently increased secretion of pituitary gonadotrophin rather than through a greater utilization of a fixed amount of gonadotrophin.

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“…Furthermore, compensatory follicular growth seems to require increased gonadotrophin levels (Greenwald, 1968;Welschen, 1972). Benson, Sorrentino & Evans (1969) and Peppler (1972), using bioassay methods, detected changes in serum gonadotrophin levels 1\p=n-\4 days after ULO.…”

mentioning

confidence: 99%

Serum Concentrations of Follicle-Stimulating Hormone and Luteinizing Hormone After Unilateral Ovariectomy in the Adult Rat

Welschen¹,

Dullaart²

1974

Journal of Endocrinology

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In the rat, unilateral ovariectomy (ULO) performed at dioestrus 2 results in compensatory follicular growth within 24 h (Welschen, 1972). Furthermore, compensatory follicular growth seems to require increased gonadotrophin levels (Greenwald, 1968;Welschen, 1972). Benson, Sorrentino & Evans (1969) and Peppler (1972), using bioassay methods, detected changes in serum gonadotrophin levels 1\p=n-\4 days after ULO. However, on the basis of the follicular response, more acute changes might be expected. Therefore, it seemed of interest to measure gonadotrophin levels at short intervals after ULO.Wistar rats (180-200 g), which had had at least three consecutive 5-day cycles, were used. ULO or sham-operation was performed under ether anaesthesia at oestrus (12.00 h) or at dioestrus 2 (12.00 h). The rats were bled and killed after a postoperative period of 0-96 h. Blood was obtained under ether anaesthesia by puncture of the ophthalmic venous plexus and was allowed to clot overnight in a refrigerator before centrifugation. Serum was stored at -20°C until assayed. Con¬ centrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were estimated in duplicate by double antibody radioimmunoassays using a micromodification and antibodies raised in rabbits against NIH-FSH-S9 and NIH-LH-S17 (kindly supplied by NIAMD, Bethesda, Md., U.S.A.). Details of the method are described elsewhere (Welschen, Osman, Dullaart, de Greef, Uilenbroek & de Jong, 1975). Data are expressed in terms of NIAMD-rat-FSH/LH-RPl Standards. The results (Fig. 1) show a significant rise in FSH levels already at 5 h after ULO regardless of whether ULO was performed at oestrus or at dioestrus 2. Periovulatory values (about 300 ng/ml) were reached. Levels returned to control values at 16 to 24 h after operation. Concentrations of LH showed large individual differences, and tended to be higher shortly after ULO. However, significant increases were only found at 72 h after ULO at oestrus and at 24 h after ULO at dioestrus 2.Recently, Howland & Skinner (1973) and Ramirez & Sawyer (1974) also reported on changes in concentrations of radioimmunoassayable FSH and LH after ULO. Howland & Skinner, measuring daily, found increased FSH levels at day 1, but not at days 2 and 3 after operation, whereas Ramirez & Sawyer, measuring every 12 h, found sharply increased FSH levels at 12 and 24 h after operation, but not at later times. Both studies indicate that LH levels were slightly increased at 12-24 h after ULO. The data available at present show that FSH levels are increased to peri-

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Influence of One or Two Ovaries on Ovulation and Ovarian Weight in the Hypophysectomized Rat

Cited by 16 publications

References 4 publications

Durational effects of hemispaying on ovarian hypertrophy and estrous cycle in albino rats

Durational effects of hemispaying on ovarian hypertrophy and estrous cycle in albino rats

Can reduced consumption of gonadotrophins account for ovarian compensation in unilaterally ovariectomized, immature mice injected with gonadotrophins?

Serum Concentrations of Follicle-Stimulating Hormone and Luteinizing Hormone After Unilateral Ovariectomy in the Adult Rat

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