Effects of Unilateral Ovariectomy before and after Mating on Growth of Corpora Lutea and Peripheral Progestagen Concentrations in Pregnant Rats1

Classical studies established that the removal of one of the paired organs produces a compensatory effect on the remaining organ. In the bovine ovary this aspect has not been examined in detail. We took advantage of follicular and luteal profiles from a previous study to retrospectively examine the effects of ovariectomy before and after ovulation on follicular dynamics of the remaining ovary in cattle. To characterise the prevalence and distribution of tyrosine kinase receptor A in the bovine ovary, the original design involved unilateral ovariectomy of cows at different stages of the periovulatory period. For the purposes of the present study, we combined data into 2 groups, a preovulatory group (n = 6 cows) and a post-ovulatory group (n = 5 cows), to provide sufficient data for statistical interpretation. The cows were examined daily by transrectal ultrasonography to determine the ovarian status. For the preovulatory group, a luteolytic dose of prostaglandin was administered when the dominant follicle of the second follicular wave reached ≥10 mm, and the ovary containing the dominant follicle was removed within 48 h. For the post-ovulatory group, ovariectomy was performed on the ovary containing the newly formed corpus luteum between Days 2 to 6 (Day 0 = ovulation). Unilateral ovariectomy was performed by colpotomy under caudal epidural anaesthesia using a chain ecraseur. After ovariectomy, cows were examined daily by ultrasonography from ovariectomy to the completion of an interovulatory interval (period between 2 ovulations). Single-point data were compared between groups by t-test, and binomial data were compared between groups by Fisher’s exact test. Double ovulations were detected in 3/6 ovariectomized in the preovulatory period and 2/5 ovariectomized in the post-ovulatory period. The first ovulation after ovariectomy tended to occur earlier in the preovulatory group than in the post-ovulatory group (P = 0.08), which was attributed primarily to the development of oversized persistent dominant follicles (~20 mm in diameter for ≥7 days in absence of a corpora lutea) in 2 of 5 cows in the post-ovulatory ovariectomy group. The interovulatory interval after ovariectomy was shorter in the post-ovulatory group than in the preovulatory group (14.6 ± 0.3 v. 20.3 ± 0.6 days; P = 0.01). No distinct patterns were detected in follicular and luteal dynamics between the pre- and post-ovulatory ovariectomy groups. The number of follicles ≥3 mm detected by ultrasonography was greater in the post-ovulatory ovariectomy group than in the preovulatory group on Days 6, 7, 8, and 16 of the first interovulatory interval after ovariectomy. In conclusion, results of this retrospective study support the concept that follicular and luteal effects of removal of one ovary are influenced by the timing of ovariectomy relative to ovulation. A prospective study involving a comparison of ovarian dynamics of the same cows before and after unilateral ovariectomy will provide a better understanding of the disruption that take place and the mechanisms controlling it. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

Download Full-text

ABSENCE OF COMPENSATORY OVARIAN HYPERTROPHY IN RATS WITH ANTERIOR HYPOTHALAMIC LESIONS

Acta Endocrinologica ◽

10.1530/acta.0.0360180 ◽

1961 ◽

Vol 36 (2) ◽

pp. 180-184 ◽

Cited By ~ 21

Author(s):

Béla Flerkó ◽

Vera Bárdos

Keyword(s):

Essential Role ◽

Ovarian Tissue ◽

Vaginal Smear ◽

Corpora Lutea ◽

Vaginal Smears ◽

Hypothalamic Area ◽

Unilateral Ovariectomy ◽

Hypothalamic Lesions ◽

Oestrogen Level ◽

Stimulation Of

ABSTRACT Absence of compensatory ovarian hypertrophy in »constant oestrus rats« from lesions in the anterior hypothalamic area suggests that nervous elements localized in this region play an essential role in the stimulation of gonadotrophin output by diminution of the blood oestrogen level. The constant vaginal oestrus after unilateral ovariectomy in the majority of animals was, however, repeatedly interrupted by vaginal smears of a dioestrous type. The appearance of a dioestrous vaginal smear in the »hypothalamic constant oestrus rats« is often associated with some luteinisation. It is assumed that diminution of the blood oestrogen level by reduction of ovarian tissue in these animals may bring about a release of LH sufficient to cause formation of corpora lutea.

Download Full-text

EFFECTS OF PROSTAGLANDIN F2α ON OVARIAN BLOOD FLOW AND VASCULAR RESISTANCE IN THE PSEUDOPREGNANT RABBIT

Acta Endocrinologica ◽

10.1530/acta.0.0790337 ◽

1975 ◽

Vol 79 (2) ◽

pp. 337-350 ◽

Cited By ~ 23

Author(s):

Per Olof Janson ◽

Ivan Albrecht ◽

Kurt Ahrén

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Cardiac Output ◽

Vascular Resistance ◽

Prostaglandin F2α ◽

Interstitial Tissue ◽

Corpora Lutea ◽

Luteal Function ◽

Direct Measurements ◽

Before And After

ABSTRACT In the search for data supporting the hypothesis that the luteolytic effect of prostaglandins (PG) is initiated by a vascular mechanism, some haemodynamic parameters including ovarian blood flow and vascular resistance were measured in pseudopregnant anaesthetized rabbits before and after exogenous administration of PGF2α. The measurements were performed on days 5–10 of pseudopregnancy induced by 500 IU HCG iv. Infusion of 50 μg/kg PGF2α iv over a one-minute period caused significant falls in cardiac output, heart rate and blood pressure after 1–3 min. Blood pressure and cardiac output were normalized after 16–49 min. Blood flow in the ovarian vein (direct measurements) decreased and returned to initial values parallel to the blood pressure and no change in resistance in the vascular bed drained by the vein was noted. Total ovarian blood flow and resistance, as measured in surgically intact ovaries before and after PG infusion, using 35 or 15 μm 169Yb and 46Sc-labelled microspheres, changed and remained constant respectively, according to the same pattern as in the direct measurements. The distribution of blood flow between the corpora lutea and the interstitial tissue of the ovary measured by 15 μm radioactive microspheres. PGF2α caused an interstitial vasodilation whereas no significant change in luteal vascular resistance was noted. Since luteal blood flow represented a predominant part of total ovarian flow in the type of ovary studied, the interstitial vasodilatation caused only negligible changes in blood flow to the whole ovary. The present study does not support the hypothesis of a PG-induced luteal blood flow reduction preceding luteolysis. The possible significance of the interstitial vasodilatation for luteal function remains to be elucidated.

Download Full-text

Changes in fibroblast growth factor 2 and its receptors in bovine follicles before and after GnRH application and after ovulation

Reproduction ◽

10.1530/rep.1.00798 ◽

2006 ◽

Vol 131 (2) ◽

pp. 319-329 ◽

Cited By ~ 51

Author(s):

Bajram Berisha ◽

Martin Steffl ◽

Werner Amselgruber ◽

Dieter Schams

Keyword(s):

Endothelial Cells ◽

Growth Factor ◽

Fibroblast Growth Factor ◽

Fibroblast Growth Factor 2 ◽

Corpora Lutea ◽

Fibroblast Growth ◽

Lh Surge ◽

Short Period ◽

Before And After ◽

Capillary Endothelial Cells

The aim of this study was to evaluate the expression pattern of fibroblast growth factor 2 (FGF2), its receptor variants (FGFR1IIIc, FGFR2IIIc) and nucleolin in time-defined follicle classes before and after GnRH application and after ovulation in the cow. Ovaries containing preovulatory follicles or new corpora lutea (CL) were collected at approximately 0, 4, 10, 20 and 25 h (follicles) and 60 h (new CL) relative to injection of GnRH to induce an LH surge (n= 5 animals per group). The expressions of FGF2 and FGFR1IIIc mRNA were significantly up-regulated only in the follicle group 4 h after GnRH (during the LH surge) with a significant down-regulation immediately afterwards. Western blot analyses showed two protein bands with at 22 and 18 kDa with apparent up-regulation beginning with the LH surge (4 h) and maximum levels 20 h after GnRH. FGF2 protein in follicles collected at 0 h (before LH surge) was localised in theca tissue (endothelial and pericytes of blood vessels) but not in granulosa cells (GCs). The FGF2 staining (by immunohistochemistry) pattern changed dramatically after the LH surge for a short period (about 2 days) and FGF2 protein was localised dominantly in the nucleus of many GCs, while most capillary endothelial cells were FGF2 immunonegative. In conclusion, the novel observation of FGF2 up-regulation and the distinct change in FGF2 localisation from theca (cytoplasm of endothelial cells) to the nucleus of GCs after the LH surge may be important for survival of GCs or for the transition of the GCs to luteal cells.

Download Full-text

THE EFFECTS OF CORPORA LUTEA REMOVAL BY UNILATERAL OVARIECTOMY IN THE PREGNANT GUINEA-PIG

Reproduction ◽

10.1530/jrf.0.0260391 ◽

1971 ◽

Vol 26 (3) ◽

pp. 391-392 ◽

Cited By ~ 1

Author(s):

R. DEANESLY

Keyword(s):

Guinea Pig ◽

Corpora Lutea ◽

Unilateral Ovariectomy

Download Full-text

Studies on Sterility and Prenatal Mortality in Wild Rabbits

Journal of Experimental Biology ◽

10.1242/jeb.23.3-4.312 ◽

1947 ◽

Vol 23 (3-4) ◽

pp. 312-331

Author(s):

PATRICIA ALLEN ◽

F. W. ROGERS BRAMBELL ◽

IVOR H. MILLS

Keyword(s):

Experimental Error ◽

Total Error ◽

Maximum Error ◽

Corpora Lutea ◽

Significant Relation ◽

Technical Problems ◽

Before And After ◽

Implantation Sites ◽

The Mean ◽

The Difference

1. The technical problems underlying the estimation and analysis of the total prenatal mortality in a mammal are reviewed, with particular reference to the rabbit. 2. The material consisted of 7137 wild rabbits, of which 5089 were females. These comprise eleven series, according to the year, locality and treatment, particulars of which are given. 3. The experimental error in counts of corpora lutea was investigated and the technique critically examined. The changes in size of the corpus luteum during pregnancy were measured and a growth curve constructed. The mean number of corpora lutea in a litter, as determined from macroscopic counts, was found to be significantly lower at the beginning and end of pregnancy than in the middle. If this is due to omissions in the counts it represents a maximum error of 6.8% of corpora lutea. Microscopic counts of the corpora lutea in freehand sections of 180 pairs of ovaries of pregnant animals were made as a control. These revealed a total error in the original counts of 6.4% of the corpora lutea, affecting 25.6% of the litters, but this was distributed evenly throughout gestation. 4. Corpora lutea atretica formed from unruptured follicles are present in 16% of the pairs of ovaries, and comprise less than 2% of all corpora lutea. They are formed at the same time as the normal corpora lutea, and there is no evidence that any are formed subsequently during pregnancy in the rabbit. 5. It is estimated that 0.23% of the follicles which ovulate produce two embryos through the liberation of two ova. 6. Transperitoneal migration of 0.37% of ova, affecting 2% of the litters, was found to occur. The probability of migration either from left to right or from right to left appeared to be equal. 7. Significant changes in the mean number of implantation sites in the uteri counted at successive stages of pregnancy were observed, and particularly a decline at the end of gestation. They are of the same order as those in the mean number of corpora lutea, which they will tend to compensate so far as estimates of loss of ova before implantation are concerned. It is by no means clear that these are due to experimental error in the counts. 8. Estimates of the loss of embryos before implantation are based on the difference between the number of corpora lutea in the ovaries and of implantation sites in the uteri, and estimates of the loss after implantation on the difference between the number of implantation sites and of developing embryos. No significant relation has been found between the loss before and after implantation respectively, and it is concluded that the loss suffered after implantation is distributed independently of that which occurs before implantation.

Download Full-text

Effects of unilateral ovariectomy before and after mating on fetal and placental growth in rats

The Anatomical Record ◽

10.1002/ar.1092200212 ◽

1988 ◽

Vol 220 (2) ◽

pp. 208-211 ◽

Cited By ~ 1

Author(s):

Ali Rahima ◽

Neville W. Bruce

Keyword(s):

Unilateral Ovariectomy ◽

Before And After

Download Full-text

Prepubertal reduction of the ovarian follicle population by combined LH-releasing hormone antagonist treatment and unilateral ovariectomy influences follicle characteristics but not the ovulation rate at first oestrus

Journal of Endocrinology ◽

10.1677/joe.0.1350439 ◽

1992 ◽

Vol 135 (3) ◽

pp. 439-446 ◽

Cited By ~ 1

Author(s):

W. A. van Cappellen ◽

E. C. M. van Leeuwen ◽

P. Kramer ◽

H. M. A. Meijs-Roelofs

Keyword(s):

Ovarian Follicle ◽

Ovarian Follicles ◽

Ovulation Rate ◽

Corpora Lutea ◽

Normal Range ◽

Juvenile Period ◽

Unilateral Ovariectomy ◽

Releasing Hormone ◽

Total Pool ◽

Lh Releasing Hormone

ABSTRACT The effect on first ovulation of the massive reduction of the total pool of ovarian follicles during the infantile and late juvenile period was studied in rats. Treatment with an LH-releasing hormone antagonist (LHRH-A) during infancy (5 mg/kg body weight on days 6, 9, 12 and 15 of life) was combined with unilateral ovariectomy performed on either day 15 (early ULO) or 2–5 days before the expected day of first ovulation (late ULO). Rats were killed on the day of first or second oestrus, when blood was collected and the (remaining) ovaries were prepared for differential counting of follicles and corpora lutea. In addition, blood was sampled 8 h after ULO and the ovaries studied histologically in the group of rats which were unilaterally ovariectomized 2–5 days before first ovulation. The time of first ovulation was not influenced by treatment with LHRH-A, early or late ULO, or a combination of LHRH-A treatment and ULO. Ovulation rate after LHRH-A treatment was decreased, but was still within the normal range in intact rats and in early ULO rats compared with saline-treated controls. Serum FSH concentrations 8 h after ULO performed 2–5 days before first ovulation were similar in saline- and LHRH-A-treated rats (845 ± 59 and 801 ± 99 (s.e.m.) μg/l respectively) and had increased compared with intact controls (216 ± 15 μg/l). Treatment with LHRH-A resulted in a reduction of more than 50% in healthy and atretic follicles, and late ULO reduced the number of healthy follicles even further. In saline-treated rats late ULO decreased the rate of atresia, but in LHRH-A-treated rats atresia was not reduced further by (late or early) ULO. It is concluded that even after massive reduction of the pool of ovarian follicles by early LHRH-A treatment combined with late or early ULO, the timing of the first ovulation was normal and ovulation rates, although somewhat lower in some LHRH-A-treated rats, were within the normal range. Journal of Endocrinology (1992) 135, 439–446

Download Full-text