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1.
The mare provides a unique experimental model for studying follicle development in monovular species. Development of antral follicles in horses is characterized by the periodic growth of follicular waves which often involve the selection of a single dominant follicle. If properly stimulated, the dominant follicle will complete development and eventually ovulate a fertile oocyte. Regulation of follicular wave emergence and follicle selection involves an interplay between circulating gonadotropins and follicular factors that ensures that individual follicles are properly stimulated to grow (or to regress) at any given stage of follicular wave development. Periodic development of follicular waves continuously occurs during most of post-natal life in the mare and is influenced by factors such as stage of oestrous cycle, season, pregnancy, age, breed and individual so that different types of follicular waves (minor or major, ovulatory or anovulatory) and different levels of activity within waves may develop under different physiological conditions. Changes in gonadotropin levels and/or in the sensitivity of follicles to circulating gonadotropins seem to account largely for these physiological variations in follicle development.  相似文献   

2.
Follicular and hormonal dynamics during the estrous cycle in goats   总被引：3，自引：0，他引：3  
Transrectal ultrasonography of ovaries was performed daily in 6 goats for 3 consecutive estrous cycles. Blood samples collected daily were measured for concentrations of FSH, inhibin A, and estradiol-17beta. Follicular and hormonal data were analyzed for associations between the follicular waves and hormonal concentrations. During the interovulatory intervals, follicular growth and regression occurred in a wave like pattern (2-5 waves), and the predominant patterns were three and four follicular waves. In addition, there was no significant difference among the diameters of dominant follicles during the growth phase of the follicular waves. The number of 3 mm follicles peaked on days 0, 7, and 11 in interovulatory intervals that had three follicular waves and on days -1, 5, 11, and 15 in those that had four follicular waves. Plasma concentrations of FSH increased around the day of follicular wave emergence and declined with the growth of follicles. Circulating FSH increased again concomitant with regression of dominant follicles in the anovulatory wave, whereas FSH levels remained low in the ovulatory wave. Inhibin A was negatively correlated with FSH, while it was positively correlated with estradiol-17beta, suggesting that inhibin A is a product of healthy growing follicles and that it contributes to the suppression of FSH secretion. In conclusion, the growth of ovarian follicles in goats exhibits a wave-like pattern, and follicular dominance is less apparent in goats. Moreover, inhibin A may be a key hormone for regulation of the follicular wave through suppression of FSH secretion in goats.  相似文献   

3.
The application of real-time ultrasonography to monitoring ovarian function in mammals has advanced the understanding of follicular dynamics and its regulation. Follicular development is a wave-like sequence of organised events. The waves consist of the synchronous growth of small (4 to 5 mm) antral follicles, followed by the selection and growth of one dominant follicle which achieves the largest diameter and suppresses the growth of the subordinate follicles. In the absence of luteal regression, the dominant follicle eventually regresses (becomes atretic) and a new follicular wave begins. The dominant follicle regulates the growth of the subordinate follicles, because the appearance of the next wave is accelerated if the dominant follicle is ablated, and delayed if the lifespan of the dominant follicle is prolonged. During bovine oestrous cycles, two or three successive waves emerge, on average, on the day of ovulation (day 0) and day 10 for two-wave cycles, and on days 0, 9 and 16 for three-wave cycles. During the oestrous cycle there are thus two or three successive dominant follicles, and the last of these ovulates. Ovarian folliculogenesis is a complex process involving interactions between pituitary gonadotrophins, ovarian steroids and non-steroidal factors. Subtle changes in the hormonal milieu regulate folliculogenesis and the emergence of a follicular wave is preceded by a small increase in the concentration of plasma follicle-stimulating hormone. The mechanisms that promote the selection of a dominant follicle have not been elucidated, but considerable progress has been made in understanding follicular development and its regulation. Most treatments designed to control the development of follicular waves have been based on the physical or hormonal removal of the suppressive effect of the dominant follicle, and the consequent controlled induction of the emergence of a new follicular wave. The studies reviewed here describe current methods for regulating the bovine ovarian cycle, interesting models for future studies, and information that may be used for improving reproductive efficiency.  相似文献   

4.
The two-wave hypothesis for follicular development during the bovine estrous cycle was tested by ultrasonically monitoring individual follicles in 10 heifers during an interovulatory interval. A dominant follicle was defined as one that reached a diameter of at least 11 mm. Subordinate follicles were defined as those that appeared to originate from the same follicular pool as a dominant follicle. A dominant follicle and its cohorts were defined as a wave. Two waves during an interovulatory interval were identified in 9 of 10 heifers. The first wave was first identified, retrospectively, on a mean of Day 0.2 +/- 0.1 (ovulation = Day 0) and gave origin to a dominant anovulatory follicle and a mean of 1.4 +/- 0.3 identified subordinates. The dominant follicle reached maximum diameter (mean, 15.8 +/- 0.8 mm) on an average of Day 7 and then decreased (P less than .04) by Day 11. The subordinate follicles increased in diameter for a few days and then regressed. The second wave was first identified on a mean of Day 10.0 +/- 0.4 and gave origin to the ovulatory follicle and a mean of 0.9 +/- 0.3 subordinates. One of the 10 heifers had 3 waves of follicular activity characterized by an anovulatory wave emerging on Day 0, another anovulatory wave emerging on Day 10, and an ovulatory wave emerging on Day 16. Results strongly supported the two-wave hypothesis but also indicated that a minority of interovulatory intervals in this heifer population may have 3 waves of follicular activity.  相似文献   

5.
The hypothesis that ovulation in response to short-term (48 h) calf removal (CR) is dependent on the developmental stage of the dominant follicle was tested in two studies. The objective of Exp. 1 was to characterize the fate of a dominant follicle following 48-h CR on d 2, 4, or 8 of a postpartum follicular wave. Ovaries of 61 beef cows were examined daily by transrectal ultrasonography starting at d 20 to 21 postpartum. Treatments were no CR (n = 14) and CR on d 2 (n = 12), 4 (n = 16), or 8 (n = 10) of first detected follicular wave. Percentage of cows that ovulated a dominant follicle following treatment was not different among groups (P = 0.62). Maximum size of dominant follicles was larger in cows that ovulated (P = 0.002) than in cows that did not ovulate. The objectives of Exp. 2 were 1) to determine whether a follicular wave could be synchronized in anestrous cows following injection of 1 mg of estradiol benzoate (EB) and 200 mg of progesterone (P4; EB + P4); 2) to characterize the fate of dominant follicles following 48-h CR at three stages of a synchronized follicular wave; and 3) to determine whether estrous cycles of normal length followed ovulation in cows pretreated with EB + P4. Ovaries of 50 anestrous beef cows were examined daily as in Exp. 1. Treatments were sesame oil (SO) injected (i.m.) on d 25 postpartum and no CR (n = 9); EB + P4 and no CR (n = 9); EB + P4 and CR on 6 (n = 12), 8 (n = 9), or 12 (n = 11) d after injection. The EB and P4 injections were given on d 25 postpartum. Variability in day of emergence of subsequent follicular waves was lower in cows receiving EB + P4 than in SO-injected cows (P < 0.05). The percentage of cows that ovulated was not different (P = 0.16), but CR increased the percentage of cows that ovulated when groups that received EB + P4 were compared to the EB + P4 group that did not have CR (53.1 vs 11.1%, respectively; P < 0.05). Maximum diameter of dominant follicles was larger (P = 0.05) in ovulatory follicles. The luteal phase was longer (P < 0.03) in cows receiving EB + P4 injection (10.6 +/- 1.2 d) than in cows receiving SO (4.4 +/- 2.2 d). In summary, the maximum size of ovulatory follicles was greater than that of nonovulatory follicles, the ovulatory response of postpartum anestrous cows was maintained through d 8 of a follicular wave, synchronization of follicular waves was accomplished in postpartum cows using EB + P4, and the subsequent luteal phase length was increased in animals that were administered EB + P4.  相似文献   

6.
Follicle Wave Growth in Cattle   总被引：1，自引：0，他引：1  
Ovarian follicle growth in cattle culminates in the selection of a single dominant follicle which attains the ability for final maturation and ovulation once or twice during the luteal phase and at the end of the oestrous cycle, as well as during other reproductive states. This review will describe in detail the first follicle wave of the cycle leading to selection of the first wave dominant follicle, indicating the specific gonadotrophin dependencies of cohort and dominant follicles, and relating follicle fate to steroidogenesis. As a differential gonadotrophin response of growing antral follicles during the follies‐stimulating hormone (FSH) decline may determine which follicle becomes selected, first wave follicles are also characterized in relation to intrafollicular growth factors, which may modify the gonadotrophin response, such as inhibins and members of the insulin‐like growth factor (IGF) family. Subsequently, the follicular control of the transient FSH rise and decline so crucial to dominant follicle selection will be discussed. It is concluded that successful hormonal manipulation of follicle wave growth and dominant follicle selection will depend on our detailed understanding of the gonadotrophin requirements of differentiating wave follicles.  相似文献   

7.
The objective of this study was to examine the follicular dynamics of five-eighths Girolando cows by observing the number of follicular development waves, days of emergence of those waves, diameters of the dominant and largest subordinate follicles and the processes of follicular selection and dominance. Ovarian follicle dynamics were monitored for 24 oestrous cycles in 12 cows, of 4 to 10 years of age, presenting regular oestrous cycles and with body scores between 3 and 4. Ovaries were observed daily for two consecutive oestrous cycles and follicles were measured with ultrasonographic equipment. The dominant follicle was considered to be that which presented a diameter ≥ 10 mm for three consecutive days and on the day of wave emergence, when a group of follicles measuring 3–5 mm in diameter would appear. Of the 24 cycles monitored, 62.5% presented two waves of follicular development and 37.5% presented three waves. The cycles presenting two waves had an average duration of 20 days, with the emergence of the waves on days 1 and 9, whereas the cycles presenting three waves had an average duration of 22 days, with emergences on days 1, 10 and 16. For cycles with two waves, both the first and second dominant follicles reached an average size of 13.8 mm, with the first regressing on day 10 and the second ovulating around day 20. For cycles with three waves, the dominant follicles of the first and second waves reached maximum diameters of 11.8 and 12 mm, respectively, with the first regressing on day 11 and the second regressing on day 17. The third dominant follicle reached a maximum diameter of 12.4 mm on day 20, and ovulated on day 22. These results lead to the conclusion that the follicular dynamics of five-eighths Girolando cows are characterized by the presence of two to three waves of follicular growth.  相似文献   

8.
During an oestrous cycle, a cohort of antral follicles develops into – depending on the species – one or more ovulatory follicles. The bovine oestrous cycle is characterized by two to three such cohorts or growth waves, only the last of which will result in an ovulation. In every growth wave, several antral follicles are recruited for development. Recruited follicles are subjected to a selection process, whereby ever decreasing levels of follicle stimulating hormone (FSH) are available to the FSH dependent follicles. In the cow, a single follicle from the cohort will acquire dominance. The ability of the dominant follicle to prosper under basic FSH levels is ascribed to a transition in hormone dependency from FSH to luteinizing hormone. The exact follicle selection mechanism remains, however, to be elucidated. The beginning of this article focuses on the recruitment, selection and dominance phases in antral follicle development. Subsequently, the conditions leading to successful maturation and ovulation are discussed. The next section expounds upon the mechanisms for exogenous modulation of follicular dynamics with the aim of superovulation/superstimulation, and finally prospective future research directions are sketched.  相似文献   

9.
The aim of this study was to characterize ir-IGF-I pattern and its relation to other hormones during the oestrous cycle in mares. Nine non-pregnant non-lactating pluriparous thoroughbred mares were used. The studied mares were examined ultrasonically and bled daily to follow the ovarian changes and the hormonal milieu for a complete Interovulatory interval (IOI). Two (minor and major) follicular waves were characterized per IOI in thoroughbred mares. The largest follicle of the first follicular wave (DF1) was firstly detected at D - 1.75 ± 0.47 with a growth rate of 2.78 ± 0.14mm/day and maximum diameter of 22.45 ± 0.75mm on day 6.65 ± 0.82. The largest follicle of the second follicular wave (DF2) had a growth rate of 2.15 ± 0.29 mm/day, reached a maximum diameter of 42.70 ± 2.63 mm on D 19.25 ± 0.43. Ir-IGF-I increased significantly prior to ovulation and had a similar pattern to oestrogen (r = 0.84, p < 0.05), suggesting that the ovarian follicles are the main source of circulating ir-IGF-I during the oestrous cycle of mares and that ir-IGF-I may be a crucial factor in follicular differentiation and maturation. In conclusion, this study demonstrated that ir-IGF-I is secreted during the oestrous phase of the cycle concomitant with the development of the future ovulatory dominant follicle, and it may act in synergy with other hormones for the selection and differentiation of the dominant follicle.  相似文献   

10.
At high altitude, hypoxia and/or oxidative stress may compromise fertility. This study tested the relative effect of short‐ or long‐term exposure to high‐altitude hypobaric hypoxia and oxidative stress in sheep on preovulatory follicle dynamics and gonadotrophin secretion. Thus, growth dynamics, stereidogenic function and competence to ovulate of preovulatory follicles, as well as FSH and LH availability throughout the entire oestrous cycle, were compared among sheep native from low and high altitude, and sheep newcomers to high altitude. The results indicates that short‐term exposure in sheep newcomers to high altitude has a deleterious effect on both the ovarian function (affecting preovulatory follicular development) and the pituitary function (diminishing plasma LH availability). On the other hand, there were no detected differences in the preovulatory follicular development in sheep adapted to high altitude for generations and, conversely, LH secretion was increased, which suggests an adaptive mechanism. The treatment with antioxidant agents during a relative short period for the time of folliculogenesis (approximately 1 month and a half) changed substantially the development of preovulatory follicles in short‐term exposed sheep to similar patterns than in sheep native and living to both high and low altitude. These results highlight the role of oxidative stress in the detriment of the reproductive function in individuals recently exposed to high‐altitude hypoxic environment.  相似文献   

11.
Follicular fluid (FF) accumulates in the antrum of the ovarian follicle. In addition, FF provides the microenvironment for oocyte development, oocyte maturation and competence, which are acquired during follicular development. Superstimulatory treatment of 1‐month‐old lambs can achieve synchronous development of numerous growing follicles. However, these growing follicles are unable to completely mature and ovulate. Furthermore, the oocytes exhibit lower competence compared with those of ewes. In this study, we utilized an isobaric tag for relative and absolute quantification (iTRAQ)‐based proteomics analysis and compare protein composition between pre‐pubertal and adult superstimulated follicle FF in sheep. In total, 243 differentially expressed proteins were identified, including 155 downregulated and 88 upregulated between lamb and ewe. Gene ontology (GO) and KEGG pathway analysis indicated that the differentially expressed proteins are involved in signal transduction, anatomical structure development, stress response, metabolic pathways, and the complement and coagulation cascades. Many of the proteins known to affect follicle development were observed in lower abundance in FF of lamb (e.g. ADAMTS9, CD14, CTNNB1, FST, GCLC, HSPG2, IGFBP2, IGFBP6, INHBA, PRL, PAPPA, POSTN, PRDX1, SERPINA1, SOD3, STC1, VEGFC, etc.). However, a higher abundance was observed for proteasome proteins. Inadequate amounts of these proteins in FF may be lead to the unique characteristics of follicular development in lamb. These differentially expressed proteins illuminate the age‐dependent changes in protein expression in the follicle microenvironment.  相似文献   

12.
With an objective to evaluate the follicular dynamics and vascularity changes in follicles and corpus luteum, the ovaries of cyclic Surti buffaloes (n = 9) were examined daily sequentially by transrectal B‐mode and colour flow mode (CFM) ultrasonography starting from the day of oestrus till the onset of next oestrus. Higher proportion of buffaloes evidenced one‐wave cycle (66.66%) compared to two‐wave cycle (33.34%) with none showing a three‐wave cycle. The dominant follicle of the first follicular wave was the ovulatory follicle and persisted for 19.70 ± 0.50 days compared to its persistence for 16.5 ± 1.45 days in a two‐wave cycle. The maximum diameter of the ovulatory follicle in a one‐wave and two‐wave cycle did not differ yet their linear growth rates were significantly lower (p < 0.01) in a one‐wave cycle. Colour flow mode examination of follicles revealed that the percentage of follicles with detectable blood flow in the subsequently determined largest follicle (dominant follicle) was not different from that in the second largest follicle before follicle deviation. The blood flow in the dominant follicle increased significantly on the day of oestrus. The mean diameter and blood flow to the corpus luteum (CL) increased linearly and significantly from Day 5 of oestrus till Day 13 after which both parameters started declining. At or around Day 16, there was precipitous fall in the blood supply to the CL and CL diameter that continued declining thereafter to reach the lowest around Day 20 of the oestrous cycle. Rise in plasma progesterone concentrations was synchronous to CL diameter and vascularity and showed significant and positive correlations. It was concluded that Surti buffaloes evidence a preponderance of one‐wave follicular growth pattern with a significant increase in the vascularity of ovulatory follicle on the day of oestrus and corpus luteum on Day 13 of the oestrous cycle.  相似文献   

13.
This study was designed to evaluate the dominant follicles development and the estradiol‐17β concentrations in non‐ovulating and ovulating post‐partum buffaloes. Sixteen Bulgarian Murrah buffaloes were submitted to transrectal ultrasonographic examination from the 1st post‐partum day until day 50, 3 days apart. The follicular diameter of the different categories of follicles and the ovulations was recorded. The animals were allocated into two groups: I (n = 6) non‐ovulating and II (n = 10) ovulating buffaloes. Serum estradiol‐17β concentrations on the days for dominant follicle registration were measured by enzyme‐linked immunosorbent assay. The results were statistically processed by analysis of variance, non‐parametric and correlation analysis. The mean intervals between calving and first dominant follicle detection differed significantly (p < .05) among the groups (19.5 ± 6.2 vs. 13.8 ± 5.1 days), while the mean intervals between registered dominant follicles from two successive waves were comparable. The mean follicular diameters for the same category follicles in both groups were similar. Different estradiol‐17β concentrations (p < .05) for the first dominant follicle between non‐ovulating (23.5 ± 7.0 pg/ml) and ovulating (33.3 ± 8.4 pg/ml) buffaloes were determined. The cumulative percentages of buffaloes with firstly detected dominant follicle and ovulating animals correlated positively (r ≥ .84; p < .05) to post‐partum days. In conclusion, non‐ovulating and ovulating post‐partum Bulgarian Murrah buffaloes showed differences in the development of the first dominant follicle and estradiol‐17β concentrations during the time of dominant follicles detection.  相似文献   

14.
The characteristics of the major follicular waves (primary and secondary) throughout estrous cycle were studied in 7 healthy Caspian mares (age, 4-15 years; weight, 198.6 ± 0.9 kg) during the breeding season. Ovarian follicular dynamics were monitored by using an ultrasound scanner equipped with a 5-MHz, B-mode, linear-array, rectal transducer throughout 2 complete estrous cycles. The diameters of antral follicles (5 mm) were measured, averaging the narrowest and widest dimensions. To detect follicular wave emergence, the diameter profile of the 3 largest follicles per ovary of each mare was determined without considering day-to-day identity of follicles but with maintenance of distinction between left and right ovaries. The primary waves originated on day 6.4 ± 0.81 (ovulation = day 0) when the mean diameter of ovarian follicles was 9.6 ± 1.05 mm. Divergence between the dominant preovulatory follicle and subordinate follicles occurred on day 13.4 ± 0.81, when the dominant follicle was 18.1 ± 2.67 mm in diameter. The intervals from emergence to divergence and from divergence to ovulation were 7 ± 0.68 and 8.7 ± 0.68 days, respectively. Secondary major follicular waves were not observed during this study. In conclusion, only 1 major follicular wave was detected in a Caspian mare, confirming the data previously described in other equine breeds. It is also indicated that the occurrence of 1 major follicular wave per cycle is a more common phenomena in equine species.  相似文献   

15.
Ovarian follicular dynamics of cattle were examined during the estrous cycle, early pregnancy and in response to PMSG. Number and size of follicles were monitored by ultrasonographic examinations. During the estrous cycle, distinct periods of follicular dominance (measured by the increase in difference in size between the largest and second largest follicle) occurred in both the luteal (Days 6-8) and proestrus (18-22) phases of the estrous cycle (two follicular waves). Associated with the well timed development of the first dominant follicle was a change in distribution of follicle numbers in small (less than 5 mm; increased on Days 2-4), medium (6-8 mm; increased on Days 3-5) and large (greater than or equal to 9 mm; increased on Days 6-9) follicular size classes. Follicular development was greater on the ovary bearing the CL for the period that the CL was present. The dominant follicle formed during the first follicular wave was capable of ovulating (6 of 8 heifers) following an injection of a synthetic analogue of prostaglandin F-2 alpha on Day 9 of the estrous cycle. During early pregnancy (Days 6-34), follicular development (size of largest follicle, number of follicles and total accumulated size of all follicles) on the ovary bearing the CL was suppressed between Days 24 and 34 of pregnancy. This was a local effect in that follicular development was sustained on the contralateral ovary. Therefore, the CL or conceptus may be regulating follicular development in a manner to help prevent luteolysis. Associated with the injection of PMSG was an initial increase in the number of small follicles followed by their recruitment into medium and large size classes leading to ovulation. Number of follicles greater than 5 mm on the Day of estrus was related (r = .97) to the number of subsequent embryos and oocytes collected. Ultrasonography is a valuable technique to monitor ovarian follicular dynamics in cattle, and can thereby be used to infer changes in physiological and endocrine states.  相似文献   

16.
Following parturition, all cows display a wave of ovarian follicular growth, but a large proportion fail to generate a preovulatory rise in estradiol, and hence fail to ovulate. Follicle-stimulating hormone (FSH) exists as multiple isoforms in the circulation depending on the type and extent of glycosylation, and this has pronounced effects on its biological properties. This study examined differences in plasma FSH, estradiol, and inhibin A concentrations, and the distribution of FSH isoforms in cows with ovulatory or atretic dominant follicles during the first postpartum follicle wave. Plasma FSH isoform distribution was examined in both groups during the period of final development of the dominant follicle by liquid phase isoelectric focusing. Cows with an ovulatory follicle had higher circulating estradiol and inhibin A concentrations, and lower plasma FSH concentrations. The distribution of FSH isoforms displayed a marked shift toward the less acidic isoforms in cows with ovulatory follicles. A higher proportion of the FSH isoforms had a pI>5.0 in cows with ovulatory follicles compared to those with atretic follicles. In addition, cows with ovulatory follicles had greater dry matter intake, superior energy balance, elevated circulating concentrations of insulin and insulin-like growth factor-I, and lower plasma nonesterified fatty acids. The shift in FSH isoforms toward a greater abundance of the less acidic isoforms appears to be a key component in determining the capability for producing a preovulatory rise in estradiol, and this shift in FSH isoforms was associated with more favorable bioenergetic and metabolic status.  相似文献   

17.
This study characterized follicular activity and oestrous behaviour from 5 to 9 days post‐calving up to the 4th ovulation postpartum (pp) in 16 multiparous (range 2–7 parities) Thai swamp buffalo cows (Bubalus bubalis), aged 4–12 years and weighing from 432 to 676 kg. Ovarian follicular activity was examined by transrectal ultrasonography (TUS) every morning. Oestrous detection was performed twice daily by direct personal observation of behaviour and for presence of clear cervical mucus discharge and indirectly by video camera recording during 21 h/day. A follicular wave‐like pattern was present before the 1st ovulation leading to short oestrous cycles. Growth rates and maximum diameters of the ovulatory follicles did not differ between the 1st and 4th ovulations. However, growth rate for non‐ovulatory dominant follicles (DF) before the 1st ovulation was lower than for the ovulatory follicle (p < 0.05). In addition, the diameter of all ovulatory follicles (14.3 ± 0.46 mm, n = 39) was significantly larger (p < 0.01) than those of the preceding last but one non‐ovulatory DF (10.8 ± 0.20 mm, n = 5), but similar to the last preceding non‐ovulatory DF diameter (12.92 ± 0.96 mm, n = 14). Short oestrous cycles were most common between the 1st and 2nd ovulations (93.75%, 15/16 cows, 10.2 ± 0.38 days) decreasing in prevalence thereafter (50%, 3/6 buffaloes, 12.0 ± 1.53 days). Oestrous signs were relatively vague around the 1st ovulation pp to become more easily detectable thereafter. This study suggests that properly fed swamp buffaloes could be mated successfully within 2 months pp, at their 2nd spontaneous ovulation, provided oestrous detection is at least performed daily at 06:00–08:00 hour.  相似文献   

18.
Epidermal growth factor (EGF) is one of the important regulatory factors of EGF family. EGF has been indicated to effectively inhibit the apoptosis of follicular cells, to promote the proliferation of granulosa cells and the maturation of oocytes, and to induce ovulation process via binding to epidermal growth factor receptor (EGFR). However, little is known about the distribution and expression of EGF and EGFR in cattle ovary especially during oestrous cycle. In this study, the localization and expression rule of EGF and EGFR in cattle ovaries of follicular phase and luteal phase at different time points in oestrous cycle were investigated by using IHC and real-time qPCR. The results showed that EGF and EGFR in cattle ovary were mainly expressed in granulosa cells, cumulus cells, oocytes, zona pellucida, follicular fluid and theca folliculi externa of follicles. The protein and mRNA expression of EGF/EGFR in follicles changed regularly with the follicular growth wave both in follicular and in luteal phase ovaries. In follicular phase ovaries, the protein expression of EGF and EGFR was higher in antral follicles than that of those in other follicles during follicular growth stage, and the mRNA expression of EGFR was also increased in stage of dominant follicle selection. However, in luteal phase ovaries, the growth of follicles was impeded during corpus luteum development under the action of progesterone secreted by granular lutein cell. The mRNA and protein expressions of EGF and EGFR in ovarian follicles during oestrous cycle indicate that they play a role in promoting follicular development in follicular growth waves and mediating the selection process of dominant follicles.  相似文献   

19.
Factors that affect ovarian follicular dynamics in cattle.   总被引：1，自引：0，他引：1  
Studies of ovarian follicular dynamics in cattle may lead to methods for improving fertility, for synchronizing estrus with more precision, and for enhancing superovulatory responses. Within an estrous cycle, two or three large (> 10 mm) follicles develop during consecutive waves of follicular growth. The last wave provides the ovulatory follicle, whereas preceding wave(s) provide follicles that undergo atresia. The life span of large follicles seems to depend on the pulsatile secretion of LH; decreased frequency of LH pulses results in atresia of large follicles. Aromatase activity in the walls of the largest follicles is greatest during the first 8 d of the estrous cycle and decreases by d 12. Steroidogenesis of the largest and second-largest ovarian follicles differs on d 5, 8, and 12 of the estrous cycle. Follicular dynamics are altered by negative energy balance and lactation. The number of large follicles and concentration of estradiol during the preovulatory period differs between postpartum lactating and nonlactating cows. Dietary fats stimulate follicular growth when they are fed to increase energy balance. Administration of bovine somatotropin decreases energy balance and has a differential effect on ovarian follicular responses; growth of the largest follicle does not change, but growth of the second-largest follicle is stimulated by somatotropin. Studies of follicular dynamics in lactating cows demonstrate changes in ovarian function associated with energy balance that may be related to inefficient reproductive performance of cows producing high yields of milk.  相似文献   

20.
Relatively few studies have been reported regarding the reproductive physiology of female Thai native cattle. Therefore, the objective of the present study was to evaluate the follicular dynamics and concentrations of follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) during the estrous cycle in Thai native heifers (TNH) and to compare obtained results with those of European and Indian cattle breeds previously reported. For the detection of estrus, ovaries of all 20 heifers were examined twice daily (12 h intervals) by ultrasonography for three consecutive estrous cycles. From data of 60 estrous cycles (n = 60 estrous cycles from 20 heifers), it was found that 14 (70%) and 6 heifers (30%) had two (42 estrous cycles collected from 14 heifers) and three follicular waves (18 estrous cycles collected from 6 heifers), respectively. The days when estrus was detected, interovulatory intervals, life‐spans of corpus lutea (CL), and days for growing and regression of CLs were shorter in the two follicular waves than those in the three follicular waves (P < 0.05). In both two and thre follicular waves, larger maximum diameters and higher growth rates of the dominant follicle (DF) in an ovulatory wave were observed than those of the preceding waves without ovulation (P < 0.05). There was a progressive increase in follicular size and FSH and E2 production during follicular growth in each follicular wave. In addition, the FSH and E2 peak concentrations during the ovulatory wave were higher than those of the anovulation waves (P < 0.05). Moreover, although the ovarian follicular dynamic patterns in Thai native heifers were similar to those previously reported for European and Indian cattle breeds, the diameter of the largest preovulatory follicle (OF), subordinate follicles (SF) and CLs were smaller than those in European and Indian cattle breeds. In conclusion, when compared with European and some breeds of Indian cattle, the length of interovulatory intervals was shorter, and the sizes of dominant SF and CLs were smaller in Thai native heifers.  相似文献   

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