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Miguel del Campo, Néstor Lagos and Hernán Lara

Introduction High testosterone plasma levels and the presence of fluid-filled follicles (cysts) that do not ovulate characterize polycystic ovary syndrome (PCOS). PCOS is the most prevalent ovarian pathology in women, affecting 5–12% of women

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Tony M Plant

evidence upon which Harris' hypothesis was based had been obtained primarily from studies of the female, most likely because ovulation was a discrete and readily detected event and, at the time, the only reliable surrogate marker of acute hypothalamic

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A Hourvitz, E Gershon, J D Hennebold, S Elizur, E Maman, C Brendle, E Y Adashi and N Dekel

Introduction The individual phases of the normal ovarian life cycle are controlled by a highly synchronized and exquisitely timed cascade of gene expression ( Richards 1994 , Richards et al. 1995 ). Ovulation, a complex process

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Qinglei Li, Fermin Jimenez-Krassel, Anilkumar Bettegowda, James J Ireland and George W Smith

Introduction Ovulation, triggered by the preovulatory luteinizing hormone (LH) surge, is a prerequisite for fertilization and embryonic development. Preovulatory degradation of the extracellular matrix at the follicle apex is a

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I. J. CLARKE, R. J. SCARAMUZZI and R. V. SHORT

SUMMARY

The ovarian activity of prenatally androgenized ewes was studied by measuring plasma progesterone concentrations in daily samples of peripheral blood, and by examining the ovaries at laparotomy.

Ewes that were exposed to testosterone between days 30 and 80, 50 and 100 or 70 and 120 of foetal life by implanting their mothers with 1 g testosterone, failed to show regular overt oestrous cycles, although some of them ovulated, whereas ewes exposed to testosterone between days 90 and 140 of foetal life had normal oestrous cycles. The incidence of ovulatory failure appeared to increase with age in ewes treated between days 50 and 100 or days 70 and 120 of foetal life.

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D. W. BULLOCK and A. V. NALBANDOV

SUMMARY

The ovarian ascorbic acid-depletion assay has been used to determine the luteinizing hormone (LH) content of plasma at different times in the laying cycle of the hen. The existence of three peaks of LH release preceding ovulation was confirmed and no fourth peak was determined. By injection of an anti-adrenergic drug (dibenzyline) to prevent ovulation, all three releases of LH were inhibited.

Preceding the missed ovulation leading to a pause in the laying cycle, no peaks of plasma LH were found. These results provide direct evidence on which theories for the hen's ovulation cycle can be assessed.

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L. E. ROWSON

Follicles in relatively large numbers (average 26) have been consistently produced by the injection of 3600 and 4500 i.u. of whole pregnant mares' serum, and to a slightly lesser degree (average 14), by the injection of similar amounts of commercial processed pregnant mares' serum.

Ovulation after this treatment has been spontaneous, but to a lesser degree when using the processed material (5·4% ovulations) than when using the whole plasma (24% ovulations).

The percentage of ovulations after this treatment has been increased by the intravenous injection of chorionic gonadotrophin at a dosage of 2000 i.u. (22% for processed material and 42% for whole serum). Where a large corpus luteum was present in the ovary during the time of treatment, the percentage ovulations was 52 as compared with only 14 in those cases in which no corpus luteum was present.

Injections of 20 mg. progesterone daily for 4 days after removal of the corpus luteum, and after the p.m.s. injections, had the same effect on the ovulation rate (55% ovulations) as the presence of a large corpus luteum.

Ova produced by either processed or whole serum can be fertilized fairly readily in the absence of a corpus luteum, but in its presence or after daily injections of progesterone, no fertilization takes place.

In the presence of a corpus luteum or after injections of progesterone, the ova travel down the Fallopian tube at a greatly increased rate, but were in some cases slowed up by the injection of oestrogens.

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Jennifer H Steel, Roger White and Malcolm G Parker

) and energy homeostasis ( Leonardsson et al. 2004 ). This review will focus on the function of RIP140 in the ovary to regulate ovulation and in adipose tissue to regulate fat accumulation. RIP140 binds to nuclear receptors in a ligand

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B. J. WEIR

SUMMARY

Forty-five adult chinchilla (Chinchilla laniger) were used to investigate the ovulatory response to pregnant mare serum (PMS) and human chorionic gonadotrophin (HCG) administered by intraperitoneal injection according to various regimes. Ovulation occurred (even during pregnancy) only when both PMS and HCG were given; 87·5% animals ovulated with a mean number of 3·7 ova, but only 26 out of the 119 ova were recovered. The range of ova ovulated per ovary was 1–7 and the range per animal was 1–12. The reasons for the low recovery rate of eggs and the general efficacy of the hormone regimes are discussed.

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MAY REED and W. F. HOUNSLOW

SUMMARY

Ovulation has been induced in the cyclic guinea-pig at a time when the ovaries contain mature follicles, by a single injection of purified luteinizing hormone (LH), follicle-stimulating hormone or guinea-pig gonadotrophins from homogenates of female guinea-pig anterior pituitaries. An injection of any one of the substances given too early only caused follicular luteinization and the ova were retained, even with increased dosage. A single injection of LH in mid-dioestrus caused 'LH effects' on the follicles (destruction of the growing follicles), giving a histological picture similar to that which obtains at the time of ovulation in the untreated animal. Homogenates of anterior pituitaries taken from donor guinea-pigs 1–2 days before ovulation was due (but not at any other time in the cycle) when injected into recipients at middioestrus had similar effects on the follicles. Donor anterior pituitaries taken from guinea-pigs in which ovulation had been inhibited by daily injections of progesterone, caused ovulation in recipients with mature ovarian follicles or 'LH effects' in those in mid-dioestrus. It is suggested that in the guinea-pig there is a basal secretion of gonadotrophins during most of the cycle. A day or two before ovulation occurs and when the ovaries already contain ripe follicles, there is a marked increase in the synthesis of LH which is then released from the anterior pituitary gland and rupture of the follicles occurs.