178 IS PROGESTERONE THE DETERMINING REGULATORY FACTOR BEHIND OVULATION RATE IN EWES?

2015 ◽  
Vol 27 (1) ◽  
pp. 180
Author(s):  
J. Sohal ◽  
V. Paravinja ◽  
T. Baby ◽  
M. Murawski ◽  
T. Schwarz ◽  
...  
Keyword(s):  
Luteal Phase ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
Antral Follicles ◽  
Follicular Waves ◽  
Lh Pulsatility ◽  
Lh Release ◽  
The Mean ◽  
Number Percentage ◽  
Ovulatory Follicles

Ovarian antral follicles in the ewe grow in an orderly succession, producing 3–4 waves per oestrous cycle. In prolific sheep, some large antral follicles from the second-last wave of the oestrous cycle are added to the ovulatory follicles emerging just before oestrus to give a higher ovulation rate; it is feasible that regression of these follicles is prevented by an increase in serum concentrations of FSH and/or LH pulsatility at pro-oestrus. Prolific sheep tend to have a shorter luteal phase than non-prolific breeds and there is a great deal of evidence that luteal progesterone (P4), in addition to regulating LH release, may govern the secretion of FSH heralding the emergence of follicular waves. The specific purpose of the present experiments was to determine whether or not extending the duration of the luteal phase would alter the ovulation rate in prolific sheep. In both studies, exogenous P4 (7.5 mg ewe–1 IM) was administered on Days 11 and 12 (Day 0 = ovulation) in moderately prolific Rideau Arcott x Polled Dorset (Exp. 1, n = 8) and highly prolific Olkuska ewes (Exp. 2, n = 7), while the equinumerous groups of animals served as controls (CTR). Transrectal ovarian ultrasonography was performed daily and jugular blood samples were drawn twice a day from Day 9 until ovulation. All single-time point observations were compared between groups by Student t-test. Progesterone injections resulted in uniform increments in serum P4 levels in all animals allocated to the treatment (TRT) groups. However, the mean duration of the interovulatory interval did not differ (P > 0.05) between TRT and CTR groups of ewes in both experiments. The mean (± s.e.m.) ovulation rate was 1.6 ± 0.2 v. 3.2 ± 0.4 (Exp. 1; P < 0.001) and 3.2 ± 0.8 v. 4.0 ± 1.0 (Exp. 2; P < 0.05) in TRT v. CTR ewes, respectively. There were no differences in terms of the timing of penultimate and final wave emergence between the two subsets of animals studied in either experiment. The number/percentage of ovulating follicles from the penultimate wave of the interovulatory interval studied was 0.25 ± 0.16 v. 1.75 ± 0.45 (P < 0.01)/25.0 ± 16.4% v. 75.0 ± 16.4% (P < 0.05) in Exp. 1 and 0.50 ± 0.30 v. 1.60 ± 0.40 (P < 0.05)/13.8 ± 9.0% v. 53.4 ± 16.7% (P < 0.05) in Exp. 2, in TRT v. CTR animals, respectively. In summary, administration of P4 at the end of diestrus reduced the incidence of ovulations from the penultimate wave of the oestrous cycle in moderately and highly prolific strains of sheep. Therefore, progesterone appears to be a key endocrine signal governing the ovulation rate in cyclic sheep, presumably by acting directly at the level of the ovary. The present results may pave a way to devising a simple and inexpensive method of controlling lamb productivity in commercial flocks of sheep and fertility in other polyovulatory species.

Studies of the oestrous cycle, oestrus and pregnancy in the koala (Phascolarctos cinereus)

Reproduction ◽  
2000 ◽  
pp. 49-57 ◽  
Author(s):  
SD Johnston ◽  
MR McGowan ◽  
P O'Callaghan ◽  
R Cox ◽  
V Nicolson
Keyword(s):  
Luteal Phase ◽  
Post Partum ◽  
Plasma Concentrations ◽  
External Genitalia ◽  
Oestrous Cycle ◽  
Phascolarctos Cinereus ◽  
Pregnant Females ◽  
Peripheral Plasma ◽  
The Mean ◽  
High Concentrations

As an integral part of the development of an artificial insemination programme in the captive koala, female reproductive physiology and behaviour were studied. The oestrous cycle in non-mated and mated koalas was characterized by means of behavioural oestrus, morphology of external genitalia and changes in the peripheral plasma concentrations of oestradiol and progestogen. The mean (+/- SEM) duration of the non-mated oestrous cycle and duration of oestrus in 12 koalas was 32.9 +/- 1.1 (n = 22) and 10.3 +/- 0.9 (n = 24) days, respectively. Although the commencement of oestrous behaviour was associated with increasing or high concentrations of oestradiol, there were no consistent changes in the morphology or appearance of the clitoris, pericloacal region, pouch or mammary teats that could be used to characterize the non-mated cycle. As progestogen concentrations remained at basal values throughout the interoestrous period, non-mated cycles were considered non-luteal and presumed anovulatory. After mating of the 12 koalas, six females gave birth with a mean (+/- SEM) gestation of 34.8 +/- 0.3 days, whereas the remaining six non-parturient females returned to oestrus 49.5 +/- 1. 0 days later. After mating, oestrous behaviour ceased and the progestogen profile showed a significant increase in both pregnant and non-parturient females, indicating that a luteal phase had been induced by the physical act of mating. Progestogen concentrations throughout the luteal phase of the pregnant females were significantly higher than those of non-parturient females. Parturition was associated with a decreasing concentration of progestogen, which was increased above that of basal concentrations until 7 days post partum.

Passively immunizing ewes against inhibin during the luteal phase of the oestrous cycle raises the plasma concentration of FSH

1989 ◽  
Vol 123 (3) ◽  
pp. 383-391 ◽  
Author(s):  
G. E. Mann ◽  
B. K. Campbell ◽  
A. S. McNeilly ◽  
D. T. Baird
Keyword(s):  
Plasma Concentration ◽  
Luteal Phase ◽  
Passive Immunization ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
Control Group ◽  
Pituitary Cells ◽  
Marked Rise ◽  
Peripheral Plasma

ABSTRACT Passive immunization was used to investigate the importance of inhibin in the negative feedback loop regulating the production of FSH in sheep. An antiserum raised to the 1–26 peptide fragment of the N-terminus of the α-chain of porcine inhibin was first shown to neutralize the suppressive effects of inhibin on the production of FSH by dispersed ovine pituitary cells in vitro. Groups of five mature Scottish Blackface ewes on day 8 of the luteal phase of the oestrous cycle were then injected with either 10 ml plasma from normal ewes (control) or 10 ml ovine inhibin antiserum. On day 10, luteal regression was induced by an i.m. injection of cloprostenol (100 μg), and ovulation rate determined 6 days later by laparoscopy. Peripheral plasma samples were collected throughout the experimental period. Following treatment, there was no change in the peripheral plasma concentration of LH in either group. Following injection of the inhibin antiserum, the concentration of FSH rose significantly (P<0·001) compared with the control group. The concentration of FSH rose from 1·42 ± 0·06 to a maximum of 2·58 ± 0·23 (s.e.m.) μg/l by 5·6 ±0·9 h, this maximum lasting 9·0±1·1 h. By 32·8 ±6·9 h, the concentration of FSH had returned to pretreatment levels, while the titre of free antibody in the plasma of treated ewes was still high. In the treated ewes, there were one single and four double ovulations compared with three single and two double ovulations in the control group, indicating that the inhibin immunization may have resulted in an increase in ovulation rate. We conclude that the marked rise in the plasma concentration of FSH following injection of inhibin antiserum provides strong evidence that inhibin is an important factor in the regulation of FSH production by the pituitary gland at this time. Journal of Endocrinology (1989) 123, 383–391

122 OVARIAN FOLLICULAR DYNAMICS IN CROSS-BRED EWES DURING THE RAINY SEASON UNDER TROPICAL CONDITIONS

2017 ◽  
Vol 29 (1) ◽  
pp. 169
Author(s):  
E. A. Reyes ◽  
D. R. Bergfelt ◽  
V. F. Ratto ◽  
X. P. Valderrama ◽  
E. Arcelay ◽  
...  
Keyword(s):  
Body Condition Score ◽  
Salt Water ◽  
Small Ruminants ◽  
Pennisetum Purpureum ◽  
Caribbean Region ◽  
Free Access ◽  
Antral Follicles ◽  
Follicular Waves ◽  
Tropical Conditions ◽  
Ovulatory Follicles

Small ruminants are an important livestock species on many island nations of the Eastern Caribbean region and serve as a vital source of food and income. This study was designed to characterise follicular development during the inter-ovulatory interval (interval between 2 consecutive ovulations) under tropical conditions. Non-lactating, 2- to 4-year-old crossbred Barbados-Black Belly × White Virgin Island ewes weighing a mean 30.4 kg with mean body condition score 2.9 (score 1–5) were used during September–November for the study. Ewes were maintained in a paddock of 100 m2 at the research farm in St. Kitts and Nevis (17.3°N, 62.7°W). Animals were fed daily with 100 g of concentrate (17% crude protein) and had free access to elephant grass (Pennisetum purpureum), mineral salt, water, and shade. Ovaries of 19 females were examined daily for 46 days by transrectal B-mode ultrasonography using a 7.5-MHz lineal array transducer (Honda HS-2200UV, MA, USA) to detect ovulations and growth and regression of antral follicles. Data were analysed using chi-square, Student t-test, or one-way ANOVA. Proportion of females with 2, 3, and 4 follicular waves was 2/19 (10.5%), 10/19 (52.6%), and 7/19 (36.8%), respectively. Mean (± SEM) length of the inter-ovulatory intervals did not differ (P = 0.9) among females with 2 (16.5 ± 0.5 days), 3 (16.3 ± 0.4 days), and 4 (16.6 ± 0.2 days) follicular waves, respectively. Mean diameter of ovulatory follicles was 4.4 ± 0.1 mm, proportion of multiple ovulations was 11/19 (57.9%), and mean number of follicular waves was 3.3 ± 0.1. Wave emergence was normalized to the first ovulation of the inter-ovulatory interval (ovulation = Day 0). Mean days of wave emergence for 2 follicular waves were Days 1.0 ± 0 and 10.0 ± 0.0; for 3 follicular waves were Days 0.7 ± 0.1, 5.6 ± 0.5, and 10.4 ± 0.3; and 4 follicular waves were Days 0.8 ± 0.3, 4.7 ± 0.6, 8.4 ± 0.5, and 11.7 ± 0.3, respectively. The inter-wave intervals were 9.0 ± 0.0 days for 2 waves; 5.1 ± 0.5 and 4.8 ± 0.3 days for 3 waves; and 3.8 ± 0.5, 3.7 ± 0.3, and 3.3 ± 0.4 days for 4 waves. Growth rate (mm/day) of the largest follicle/wave did not differ (P = 07) among animals with 2 follicular waves (1.2 ± 0.7 v. 1.1 ± 0.0) or 3 follicular waves (0.9 ± 0.1 v. 0.9 ± 0.1 v. 1.2 ± 0.2). However, in animals with 4 follicular waves, the largest follicle grew faster (P < 0.05) for wave 1 (1.3 ± 0.2) than that of waves 2 (0.5 ± 0.2), 3 (0.6 ± 0.1), and 4 (0.6 ± 0.1). In conclusion, length of inter-ovulatory intervals, emergence of antral follicles, growth, and regression follicles in a wave-like pattern, inter-wave intervals, and diameter of ovulatory follicles in cross-bred ewes under tropical conditions are comparable to that described in sheep from temperate climates.

Source of ovarian inhibin secretion during the oestrous cycle of the sheep

1989 ◽  
Vol 123 (2) ◽  
pp. 181-188 ◽  
Author(s):  
G. E. Mann ◽  
A. S. McNeilly ◽  
D. T. Baird
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Venous Blood ◽  
Contralateral Side ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Secretion Rate ◽  
Antral Follicles ◽  
Luteal Tissue

ABSTRACT The source of inhibin secretion by the ovary in the sheep at different stages of the oestrous cycle was investigated by in-vivo cannulation of the ovarian veins. Twenty-four Scottish Blackface ewes were allocated to four groups of six ewes, i.e. those operated on during the luteal phase (day 10), and those operated on during the follicular phase 24–30, 36 and 60 h following an injection of 125 μg cloprostenol on day 10 of the luteal phase. Samples of jugular and timed ovarian venous blood were collected under anaesthesia before and after enucleation of the corpus luteum. Ovaries were then removed and follicles dissected out. Following injection of cloprostenol, luteal regression occurred as indicated by a fall in the secretion of progesterone. The concentration of inhibin in jugular venous plasma and its ovarian secretion rate were similar at all stages of the follicular phase and during the luteal phase. In contrast, the secretion rate of oestradiol rose from 2·68 ±0·73 pmol/min during the luteal phase to 8·70± 2·24 pmol/min 24 h after injection of cloprostenol (P<0·05). Following enucleation of the corpus luteum the secretion rate of progesterone fell from 809 ± 270 pmol/min to 86 ± 30 pmol/min (P<0·001). There was also a smaller, artifactual fall in the secretion rate of oestradiol following enucleation of the corpus luteum, which was of similar size to a fall seen in the secretion rate of inhibin. This resulted in a significant (P<0·001) fall in the ratio of progesterone to inhibin, while the oestradiol to inhibin ratio remained unchanged. The secretion rate of inhibin from ovaries containing luteal tissue was similar to that from the contralateral side without luteal tissue (1·41±0·30 compared with 1·32±0·30 ng/min), while ovaries with large antral follicles secreted significantly (P< 0·001) more inhibin than those with no follicles ≥3 mm (2·28 ± 0·36 compared with 0·25 ±0·06 ng/min). From these results we conclude that, in the sheep, large antral follicles are responsible for most, if not all, the secretion of inhibin by the ovary at all stages of the oestrous cycle, and that the corpus luteum secretes little or no immunoactive or bioactive inhibin. Due to the fact that, unlike inhibin, the secretion rate of oestradiol rises during the follicular phase of the cycle, when the concentration of FSH is suppressed, it seems likely that oestradiol rather than inhibin is the major ovarian factor modulating the change in FSH secretion seen at this stage of the oestrous cycle. Journal of Endocrinology (1989) 123, 181–188

Progesterone as the driving regulatory force behind serum FSH concentrations and antral follicular development in cycling ewes

2011 ◽  
Vol 23 (2) ◽  
pp. 303 ◽  
Author(s):  
Tanya E. Baby ◽  
Pawel M. Bartlewski
Keyword(s):  
Luteal Phase ◽  
Follicular Development ◽  
Treated Group ◽  
Time Frame ◽  
Oestrous Cycle ◽  
Control Group ◽  
Corpora Lutea ◽  
Follicular Waves ◽  
Follicular Wave ◽  
And Control

Ovarian antral follicles in sheep grow in an orderly succession, producing typically three to four follicular waves per 17-day oestrous cycle. Each wave is preceded by a transient increase in circulating FSH concentrations. The mechanism controlling the number of recurrent FSH peaks and emerging follicular waves remains unknown. During the ewe’s oestrous cycle, the time between the first two FSH peaks and days of wave emergence is longer than the intervals separating the ensuing FSH peaks and follicular waves. The prolonged interpeak and interwave interval occurs early in the luteal phase when low levels of progesterone are secreted by developing, or not fully functional, corpora lutea (CL). The purpose of the present study was to determine the effect of varying progesterone (P4) levels on circulating concentrations of FSH and antral follicular development in sheep. Exogenous P4 (15 mg per ewe, i.m.) was administered twice daily to six cycling Rideau Arcott × Dorset ewes from Day 0 (ovulation) to Day 4 (the mean duration of the interwave interval); six animals served as controls. Follicular growth was monitored in all animals by daily transrectal ultrasonography (Days 0–9). Jugular blood samples were drawn twice a day from Day 0 to Day 4 and then daily until Day 9 to measure systemic concentrations of P4, FSH and 17β-oestradiol (E2). The first FSH peak after ovulation was detected on Days 1.5 ± 0.2 and 4.2 ± 0.2 in treated and control ewes, respectively (P < 0.05). The next FSH peak(s) occurred on Day 3.9 ± 0.3 in the treated group and on Day 6.4 ± 0.5 in the control group. Consequently, the treated group had, on average, three follicular waves emerging on Days 0, 3 and 6, whereas the control group had two waves emerging on Days 0 and 5. Mean serum E2 concentrations were greater (P < 0.05) in control compared with treated ewes on Days 1.3, 2.3, 3.3, 4.0 and 4.3 after ovulation. In summary, creation of mid-luteal phase levels of P4 in metoestrus shortened the time to the first post-ovulatory FSH peak in ewes, resulting in the emergence of one more follicular wave compared with control ewes during the same time frame. Therefore, P4 appears to be a key endocrine signal governing the control of periodic increases in serum FSH concentrations and the number of follicular waves in cycling sheep.

Secretion patterns of luteinising hormone, follicle-stimulating hormone and 17β-oestradiol during oestrus and the mid-luteal phase of the oestrous cycle in mithun (Bos frontalis)

2006 ◽  
Vol 18 (6) ◽  
pp. 619 ◽  
Author(s):  
A. Dhali ◽  
D. P. Mishra ◽  
M. Karunakaran ◽  
A. Mech ◽  
C. Rajkhowa
Keyword(s):  
Luteal Phase ◽  
Luteinising Hormone ◽  
Regulatory Mechanism ◽  
Follicle Stimulating Hormone ◽  
Peripheral Circulation ◽  
Oestrous Cycle ◽  
Pulsatile Secretion ◽  
Basal Plasma ◽  
Lh Release ◽  
Stimulating Hormone

The present study reports the pulsatile secretion of gonadotrophins and 17β-oestradiol (OE2) on the day of oestrus and at the mid-luteal phase of the oestrous cycle in mithun (Bos frontalis). The frequency of luteinising hormone (LH) and follicle-stimulating hormone (FSH) pulses was found to be greater (P < 0.05) on the day of oestrus than at the mid-luteal phase. In contrast, the amplitude of the LH and FSH pulses was greater (P < 0.01) at the mid-luteal phase than on the day of oestrus. A synchronised (P < 0.01) LH and FSH secretion pattern was found only at the mid-luteal phase. A pulsatile secretion pattern for OE2 in the peripheral circulation was evident for both phases of the oestrous cycle. The frequency of the OE2 pulses did not differ significantly in different phases of the oestrous cycle. In contrast, the amplitude of the OE2 pulses and the basal OE2 concentration were found to be greater (P < 0.01) at the mid-luteal phase than on the day of oestrus. A synchronised (P < 0.01) LH and OE2 secretion pattern was observed in both phases of the oestrous cycle. In contrast, a synchronised (P < 0.05) FSH and OE2 secretion pattern was found only on the day of oestrus. In conclusion, a different pattern of LH and FSH secretion was observed in both phases of the oestrous cycle, mainly on the day of oestrus, which indicates a differential regulatory mechanism of LH and FSH release. In addition, as in cattle, OE2 exerts a positive feedback on LH and FSH release on the day of oestrus and on LH release at the mid-luteal phase of the oestrous cycle in mithun. Also, as in cattle, the greater basal plasma OE2 concentration and increased amplitude of OE2 pulses exert a negative feedback on FSH release at the mid-luteal phase of the oestrous cycle.

240 RELATIONSHIP BETWEEN PEAK NUMBER OF ANTRAL FOLLICLES AND FOLLICULAR WAVES, HORMONE CONCENTRATIONS, SUPEROVULATORY RESPONSE, AND EMBRYO QUALITY IN BEEF HEIFERS

2006 ◽  
Vol 18 (2) ◽  
pp. 228 ◽  
Author(s):  
F. Ward ◽  
P. Lonergan ◽  
F. Jimenez-Krassel ◽  
J. J. Ireland ◽  
A. C. O. Evans
Keyword(s):  
Recovery Rate ◽  
Embryo Quality ◽  
Corpora Lutea ◽  
Beef Heifers ◽  
High Group ◽  
Estrous Cycles ◽  
Antral Follicles ◽  
Peak Number ◽  
Follicular Waves ◽  
The Mean

Recent studies in dairy cattle demonstrate that the number of antral follicles during follicular waves is highly variable among animals, but highly repeatable within individuals, and the numbers of follicles during waves are inversely associated with serum FSH concentrations (Burns et al. 2005 Biol. Reprod. 73, 54-62). The aims of this study were to determine (1) serum FSH and estradiol concentrations during follicular waves in beef heifers categorized according to peak number of antral follicles per wave, and (2) the relationship between this categorization and superovulatory response. Estrous cycles of crossbred beef heifers (n = 90) were synchronized with two i.m. injections of PGF2� 11 days apart; animals were scanned daily for 5 days beginning 24 h after the second PG injection to determine the number of follicles during the first follicle wave in two or three consecutive estrous cycles. Heifers were grouped based on the peak number of follicles e 3 mm per wave in diameter (Low: d 15 follicles, n = 12; High: e 25 follicles, n = 11). Intermediate animals were excluded. Heifers were then re-synchronized and blood samples taken every 8 h up to Day 7 to characterize FSH and estradiol profiles. Subsequently, animals were superovulated (pFSH, Folltropin�; Bioniche Animal Health, Belleville, Ontario, Canada), inseminated, and flushed on Day 7; this procedure was repeated twice. All values for hormone concentrations were aligned relative to the peak FSH value. A mixed model, repeated-measures approach was used to determine if serum FSH and estradiol concentrations were different between groups. Differences in recovery rate (number of oocytes/embryos recovered compared to number of corpora lutea) and proportion of transferable embryos were analyzed using Chi-square analysis. The mean (�SE) peak postovulatory FSH concentration was lower (P d 0.03) for animals with high numbers of follicles. No differences in estradiol concentrations were observed. The mean superovulatory response (number of corpora lutea) was higher (P d 0.05) in the High group than in the low group (17.6 � 3.6 vs. 8.5 � 1.1). While there was no difference in the recovery rate of embryos (62 vs. 60%), significantly more (P d 0.05) oocytes/embryos (10.6 � 2.7 vs. 4.7 � 0.7) and transferable embryos (5.4 � 1.3 vs. 3.8 � 0.8) were recovered per animal in the High group. Of the embryos recovered, the proportion of transferable quality was higher for animals in the Low group (80 vs. 51%; P d 0.05). In conclusion, the number of antral follicles during a follicular wave in beef heifers is inversely related to peak postovulatory FSH concentration, but is unrelated to estradiol concentration. In addition, while the superovulatory response and number of transferable embryos were greater in animals with a high number of antral follicles, embryo quality, measured as the proportion of transferable embryos per donor, was reduced. We conclude that cattle with relatively high numbers of follicles per wave respond best to standard superovulation protocols. However, the reason the proportion of high quality embryos is reduced in cattle with high vs. low numbers of follicles per wave is unknown.

Induction of haemorrhagic anovulatory follicles in mares

2008 ◽  
Vol 20 (8) ◽  
pp. 947 ◽  
Author(s):  
O. J. Ginther ◽  
M. O. Gastal ◽  
E. L. Gastal ◽  
J. C. Jacob ◽  
M. A. Beg
Keyword(s):  
Prostaglandin F2α ◽  
Post Treatment ◽  
Oestrous Cycle ◽  
Follicular Waves ◽  
Follicular Wave ◽  
High Incidence ◽  
The Future ◽  
The Mean

A follicular wave and luteolysis were induced in mares by ablation of follicles ≥6 mm and treatment with prostaglandin F2α (PGF) on Day 10 (where ovulation = Day 0). The incidence of haemorrhagic anovulatory follicles (HAFs) in the induced waves (20%) was greater (P < 0.007) than in preceding spontaneous waves (2%). Hormone and follicle dynamics were compared between induced follicular waves that ended in ovulations (ovulating group; n = 36) v. HAFs (HAF group; n = 9). The day of the first ovulation or the beginning of HAF formation at the end of an induced wave was designated as post-treatment Day 0. The mean 13-day interval from Day 10 (PGF and ablation) to the post-treatment ovulation was normalised into Days 10 to 16, followed by Day –6 to Day 0 relative to the post-treatment ovulation. Concentrations of LH were greater (P < 0.05) in the HAF group than in the ovulating group on Days 10, 11, 12, 14, –3 and –2. The HAF group had greater (P < 0.003) LH concentrations on Day 10 of the preceding oestrous cycle with spontaneous ovulatory waves. The diameter of the largest follicle was less (P < 0.05) in the HAF group on most days between Day 13 and Day –1 and this was attributable to later (P < 0.002) emergence of the future largest follicle at 6 mm in the HAF group (Day 12.4 ± 0.5) than in the ovulating group (Day 11.3 ± 0.1). The results indicate that the high incidence of HAFs after PGF and ablation was associated with later follicle emergence and immediate and continuing greater LH concentration after PGF treatment, apparently augmented by an inherently high pretreatment LH concentration.

Comparisons between peripheral progesterone concentrations in cyclic and pregnant Landrace x large White and Meishan gilts

1994 ◽  
Vol 6 (6) ◽  
pp. 777 ◽  
Author(s):  
CJ Ashworth ◽  
AW Ross ◽  
CS Haley
Keyword(s):  
Luteal Phase ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
Large White ◽  
Blood Samples ◽  
Breed Differences

Progesterone concentrations were determined in blood samples collected twice daily (at 0900 and 1700 hours) from the day of oestrus (Day 0) until Days 15-24 in ten Landrace x Large White gilts (four cyclic and six pregnant gilts) and eight Meishan gilts (four cyclic and four pregnant gilts). Progesterone concentrations during the early luteal phase tended to be higher in pregnant Meishan gilts than in pregnant Landrace x Large White gilts. Furthermore, when differences in ovulation rate and peak progesterone concentrations were accounted for, maximum progesterone concentrations occurred earlier in Meishan gilts than in Landrace x Large White gilts (P < 0.01); this difference was particularly marked when pregnant animals of the two breeds were compared. In non-mated animals, analyses of the timing and magnitude of progesterone concentrations observed towards the end of the oestrous cycle revealed that the decrease in progesterone concentrations occurred earlier (P < 0.05) in Meishan gilts. Such breed differences in the peripheral progesterone profile may be associated with reduced prenatal mortality, a characteristic of Meishan females.

Participation of the superior ovarian nerve in the regulation of compensatory ovarian hypertrophy: the effects of its section performed on each day of the oestrous cycle

1994 ◽  
Vol 140 (2) ◽  
pp. 197-201 ◽  
Author(s):  
R Chávez ◽  
R Domínguez
Keyword(s):  
Left Ovary ◽  
Oestrous Cycle ◽  
Ovulation Rate ◽  
Adult Rats ◽  
Superior Ovarian Nerve ◽  
Neural Information ◽  
The Mean ◽  
The Right

Abstract The effects were analysed of section of the superior ovarian nerve on compensatory ovulation and ovarian hypertrophy, in adult rats with the left or right ovaries extirpated during the oestrous cycle and autopsied 6 or 20 days later. Rats with hemiovariectomy or hemiovariectomy plus denervation recovered their oestrous cyclicity between 2 and 3 days after surgery. Six days after hemiovariectomy 14 out of 17 rats ovulated on the expected day of oestrus. All the animals were hemiovariectomized on the day of pro-oestrus. The mean ± s.e.m. number of ova shed was similar to the group of animals with both ovaries (7·8 ± 1·2 vs 9·5 ± 0·2 Compensatory ovarian hypertrophy was observed in the right ovary when left hemiovariectomy was performed on day 2 of dioestrus or pro-oestrus; similar results were observed in the left ovary when the right one was extirpated at oestrus or pro-oestrus. Section of the right superior ovarian nerve in left-hemiovariectomized rats caused a reduction in ovulation rate and number of ova released. Compensatory ovarian hypertrophy was modified in the opposite way by unilateral section of the superior ovarian nerve to the in situ ovary depending on the day of the cycle when hemiovariectomy was performed. Twenty days after treatment, ovulation rate, compensatory ovulation and ovarian hypertrophy were similar in both left- or right-hemiovariectomized rats. Compensatory ovarian hypertrophy increased in all animals with section of the superior ovarian nerve, except when hemiovariectomy was carried out at oestrus or the left ovary was extirpated on day 1 of dioestrus. The results suggest that modulation of compensatory ovarian hypertrophy by neural information arriving at the ovary by way of the superior ovarian nerve varies during the oestrous cycle. Journal of Endocrinology (1994) 140, 197–201

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