Ultrasonic evaluation of the reproductive tract of the mare: Ovaries

Ultrasonography is useful for monitoring the dynamic follicular and luteal changes of equine ovaries, since it permits rapid, visual, non-invasive access to the reproductive tract. A 5 MHz transducer has greater resolving power and is far more suitable for evaluation of ovaries than a 3–3.5 MHz transducer. Follicles as small as 2–3 mm can be seen and the corpus luteum can usually be identified throughout its functional life. In a study involving daily ovarian examinations, there was a pronounced change in shape of the preovulatory follicle from a roughly spherical to a pear-shaped or oblong form in 66% of the ovulatory periods, This change usually occurred on the day preceding ovulation. The occurrence of ovulation was detectable by the disappearance of a large follicle. In addition, the ovulation site on day 0 was characterized by an intense echogenic area in 88% of 32 ovulations. The developing corpus luteum retained the echogenicity for a mean of 2.4 days. In a blind study, the location of the corpus luteum, as determined by ultrasound, agreed with a previous independent determination of the side of ovulation by palpation in 88% of the 40 bred mares on days 0–14. In all of the 12 mares that were in estrus, the location of the corpus luteum could not be ascertained. In another study, the corpus luteum was identified for a mean of 16 days in 14 estrous cycles. One or more days before the corpus luteum became ultrasonically unidentifiable, it developed increased echogenicity in 36% of the mares, indicating greater tissue density. It is concluded that ultrasonic evaluation of the corpus luteum is superior to digital evaluation by rectal palpation. Some of the potential applications of ultrasonic examination of the ovaries include: 1) obtaining important, sometimes definitive, information by a single examination for judging whether a mare has entered the ovulatory season, 2) aiding in estimating the stage of the estrous cycle, 3) detecting double preovulatory-sized follicles which are in close apposition and difficult to discern by palpation, 4) detecting failure of ovulation or anovulatory estrus by the absence of a corpus luteum, 5) differentiating a persistent corpus luteum from anovulatory or anestrous conditions, 6) diagnosing certain pathological conditions such as peri-ovarian cysts and ovarian tumors, and 7) diagnosing anovulatory hemorrhagic follicles.     

双峰驼卵巢的形态观察

在冬春季节里,通过对87个双峰驼卵巢进行观察测量,研究其形态及卵泡、黄体数量分布情况.空怀的双峰驼的卵巢上可看到许多大小不同的卵泡、红体、黄体.在整个发情期都有较多的卵泡分布,其卵泡和黄体明显突出,形状一般为球形或者半球形,边界清晰,与其它哺乳动物明显不同.单个卵巢卵泡数最多可达69个,直径最大可达3.31 cm,黄体...     

Possible actions of tumor necrosis factor-alpha in ovarian function

Tumor necrosis factor-alpha (TNFalpha) is a multifunctional cytokine that was first described as a tumoricidal factor produced by activated macrophages. Extensive research over the last two decades has suggested that TNFalpha has physiologically diverse actions in ovarian function in a variety of species. TNFalpha and its specific receptors are present in the ovaries of many species. Furthermore, TNFalpha plays multiple and probably important roles in corpus luteum (CL) function as well as ovarian cell function throughout the estrous cycle. This review focuses on recent studies documenting TNFalpha in ovarian follicles and CL in several mammals. In addition, possible roles of TNFalpha in ovarian function throughout the estrous cycle and in the gestation period are discussed.     

Induction of ovulation in proestrous ewes: Identification of the ovulatory follicle and functional status of the corpus luteum

Ewes were treated with a luteolytic agent on Day 14 of the estrous cycle. Their largest follicle was identified 30 hr later. Thirty-six hr post-treatment, ewes received an injection of an analog of luteinizing hormone-releasing hormone (LHRHa). The peak in the induced surge of LH occurred 2 to 4 hr after injection of LHRHa. Ovulation occurred from the largest follicle approximately 24 hr following administration of LHRHa. During the subsequent luteal phase, serum concentrations of progesterone were normal. The treatment regimen described is well-suited for collection of follicles at precisely-timed periovulatory intervals. Perhaps information gained by using this model will be useful in ultimately understanding the follicular events associated with ovulation and function of the corpus luteum.     

牛卵巢黄体状况与腔前卵泡采集数量的关系

根据牛离体卵巢黄体的不同状况，将31枚卵巢分为5种类型，并采用机构方法分离腔前卵泡，观察不同黄体状况卵巢与腔前卵泡采集数量的关系，结果表明，火山口型，圆锥型和蘑菇型3种大黄体的卵巢腔前卵泡采集量多，扁平片状和表面无黄体型卵巢腔前卵泡采集量较少，具有黄体状况的卵巢初级卵泡（Pm)采集数量多于无黄体类型卵巢，原始卵泡（Pf) 以3种黄体较大的卵巢采集数量最多，次级卵泡（Sc)则以黄体为火山口型卵巢为最多，说明卵巢黄体状况不同，其腔前卵泡采集数量有所不同。     

The localization and expression of epidermal growth factor and epidermal growth factor receptor in bovine ovary during oestrous cycle

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.     

藏绵羊卵巢组织学及卵泡超微形态的观察

旨在通过观察藏绵羊卵泡、黄体的组织学特征及卵泡的超微形态,探讨其与生理功能的关系.本研究运用大体解剖、常规组织切片和H.E染色及透射电镜技术对藏绵羊卵巢卵泡和黄体的组织结构特点以及卵泡的超微形态进行观察和分析.结果发现,藏绵羊黄体期和卵泡期卵巢的宽度和厚度存在显著差异(P＜0.05),而重量和长度无显著差异(P＞0.0...     

Characteristics of oestrous cycles in Holstein cross-bred dairy heifers: An evidence of delayed post-ovulatory progesterone rise

The aims of the current study were to illustrate figures for the characteristics of oestrous cycles especially on follicular dynamics, corpus luteum and changes in progesterone and prostaglandin F2alpha, in the Holstein cross-bred dairy heifers. Twenty six healthy and sexual-mature virgin heifers were monitored for signs of oestrus. Their ovaries were sonically examined and the numbers and the sizes of the follicles as well as of the corpus luteum were documented. In our study, no difference in ratio of the 2-wave and 3-wave patterned cycle was evident. Seasons' change did not affect on characteristics oestrous cycles as well as on dynamics of follicles and corpus luteum. The heifers showed high variation in manifesting oestrus especially on a number of hours. The ‘bodily’ oestrous signs lasted longer than did ‘behavioural’ signs and connection of lowering of the back to standing oestrus was established. Certain diversities comparing to of existed dairy breeds were drawn for follicular dynamics, corpus luteum and its progesterone: 1) the 1st an-ovulatory dominant follicles showed higher growth rate and earlier exceeded dominant diameter; 2) the follicle tended to quicker ovulate but with a smaller diameter at ovulation; 3) the corpus luteum exhibited 4−16.5 mm in diameter of central cavity. Connecting to the levels of progesterone, 4) the corpus luteum turned into active, as well as mid-luteal, period quite late, and 5) the duration of the active period of the corpus luteum was shorter, but 6) at the end of the cycle –around the day of oestrus, progesterone remained certain low but significant levels. In conclusion, the Holstein cross-bred dairy heifers in our study faced a problem of delayed post-ovulatory progesterone rise of which underlying causes are needed to be further scrutinised either at endocrine or at cell levels.     

Effect of ovarian follicles on luteal regression in heifers

Our objectives were to determine whether or not ovarian follicles contribute to spontaneous luteal regression in heifers and, if so, when during diestrus do follicles exert their effect. Thirty-one Holstein heifers having displayed at least one estrous cycle (19 to 21 d) were assigned, as available, to randomized blocks for a factorial experiment. Reproductive organs were exposed through a midventral incision on d 9, 12 or 15 postestrus (estrus = d 0). Visible follicles were electrocauterized and both ovaries were x-irradiated (1,500 rads) in treated heifers, whereas ovaries of controls were exteriorized but follicles were not destroyed and ovaries were not x-irradiated. In two additional heifers, the ovary containing the corpus luteum was exteriorized and x-irradiated on d 15 postestrus, but follicles were not electrocauterized. Jugular blood was collected before and every 8 h after surgery until d 24 postestrus. All heifers were ovariectomized on d 24 postestrus to inventory follicles and to weigh corpora lutea. No follicles (greater than or equal to 1 mm diameter) were observed in ovaries from treated animals and concentrations of estradiol-17 beta did not change over time, whereas different numbers of follicles were observed in ovaries from controls and concentrations of estradiol-17 beta increased (P less than .05) during proestrus. Hence, treatment destroyed follicles and prevented follicular development. On d 24 postestrus, corpora lutea from treated heifers (5.5 +/- .5 g) were heavier (P less than .001) than corpora lutea from controls (1.1 +/- .1 g), independent of day when follicles were destroyed.(ABSTRACT TRUNCATED AT 250 WORDS)     

绵羊发情周期中VEGF在卵巢中的表达

应用免疫组化方法结合计算机图像分析技术,分析同期发情后0、5、9、12、15d的绵羊卵巢中血管内皮生长因子（Vascular endothelial growth factor,VEGF）表达强度变化,以期了解VEGF在绵羊卵巢发情周期不同时期的表达规律。结果显示：VEGF阳性目标主要出现于卵泡膜与颗粒细胞。原始卵泡、初级卵泡、次级卵泡VEGF表达依次增强（P〈0．05）。发情周期0～5d,大窦腔卵泡（颗粒细胞4～8层）VEGF表达量骤然上升（P〈0．05）,而9d开始显著下降,与5d比较差异显著（P〈0．05）。12d继续下降（P〈0．05）且为最低值,15d又明显上升（P〈0．05）。VEGF在卵巢间质呈弱表达,各个时期之间差异不显著（P〉0．05）。结果表明,绵羊卵巢存在着血管周期性新生的变化特点,而VEGF在这种周期性血管新生过程中起着重要的调控作用。     

猪卵巢细胞中凋亡抑制因子cFLIP在卵巢卵泡和黄体中的表达

采用免疫组织化学法检测猪卵巢中细胞凋亡调控蛋白即细胞内FLICE样抑制蛋白（Cellular FLICE-like inhibitory protein,cFLIP）在猪卵巢卵泡和黄体中的表达水平。结果显示,在健康卵泡和功能性黄体中均能够观察到cFLIP的高度表达,而闭锁卵泡和退化黄体中cFLIP的表达显著减弱。结果表明,cFLIP作为一种细胞凋亡抑制因子,参与猪卵巢中的卵巢闭锁和黄体退化。     

卵巢大小及发育状况与牛腔前卵泡采集数量的关系

用简单机械分离法处理了 12 7枚成年牛卵巢。结果显示 ,在外观正常的卵巢中 ,腔前卵泡的采集数量与卵巢的大小成正相关关系 ,而有无黄体与腔前卵泡的采集数量无明显关系 ;卵巢上不同大小的可见卵泡的数量和分布与腔前卵泡的采集量有关。卵巢上可见卵泡分布均衡 ,大、中、小卵泡均有分布 ,小卵泡不过多以及无大卵泡 ,但中、小卵泡较多的 ,无论是否有黄体存在 ,均可获得较多腔前卵泡。而卵巢表面脂肪化、卵巢充血、有弥散性片状黄体及幼稚卵巢的 ,则腔前卵泡分离很少或几乎分离不到     

Effect of day of the estrous cycle at the initiation of a timed artificial insemination protocol on reproductive responses in dairy heifers

Our objectives were to identify stages of the estrous cycle at which initiation of a timed artificial insemination (Ovsynch/TAI) protocol may reduce pregnancy rates and to monitor ovarian follicle dynamics and corpus luteum development after initiation of the Ovsynch/TAI protocol at different stages of the cycle. Cycling Holstein heifers (n = 24) were injected twice with prostaglandin F2alpha to induce estrus and were scanned by ovarian ultrasonography to determine the day of ovulation (d 0). Heifers were assigned to initiate the Ovsynch/TAI protocol at d 2 (n = 5), 5 (n = 5), 10 (n = 4), 15 (n = 5), or 18 (n = 5) of the cycle. The Ovsynch/TAI was initiated with an injection of gonadotropin-releasing hormone agonist followed 7 d later with an injection of prostaglandin F2alpha. At 36 h after injection of prostaglandin F2alpha, heifers were injected with gonadotropin-releasing hormone agonist and inseminated 16 h later. Heifers were scanned daily during the Ovsynch/TAI protocol and every other day after insemination until 16 d later. Blood samples were collected daily starting at the 1st day heifers were scanned and continued until 16 d after insemination. Initiation of the Ovsynch/TAI protocol at d 15 of the estrous cycle caused heifers to ovulate prior to insemination. A shortened return to estrus (< 16 d) was caused by ovulation failure to the second gonadotropin-releasing hormone injection, by incomplete regression of the corpus luteum, and by short life-span of the induced corpus luteum. Day of the cycle in which the Ovsynch/TAI protocol is initiated affects dynamics of follicular development, plasma progesterone profiles, and occurrence of premature ovulation. Size of the pre-ovulatory follicle was associated positively with subsequent progesterone concentrations following insemination.     

Morphological study of the corpus luteum in the rat

The cyclic related growth and regression of the corpus luteum during four consecutive oestrous cycles of the regular four-day-cycling (ie, 16 days), virgin albino Wistar rat were followed up by light and electron microscopic investigation of the ovaries. After ovulation, follicular granulosa cells differentiated into luteal cells in the newly formed corpus luteum. Based on their specific histological characteristics, four various types of corpus luteum in each stage of the oestrous cycle could be identified. As soon as the luteal cells started to degenerate, the number of fibroblasts progressively increased and apoptotic degeneration of luteal cells was initiated and became most prominent during oestrus. Complete regression of the corpus luteum was seen after 15 days. This study shows a strictly organised pattern of luteal cell growth and degeneration in the corpus luteum of the regular four-day-cycling, virgin Wistar rat. The morphological alterations may be regulated by a hormonal fluctuation.     

Intrafollicular Concentrations of Steroid Hormones and PGF2α in Relation to Follicular Development in the Mares during the Breeding Season

The concentrations of androstenedione, estradiol-17β, progesterone and PGF_2α contained in the follicular fluid produced by the follicles in collected ovaries of mares that have had estrous phase during the breeding season were measured and analyzed the relation between the growth stage of follicles and the hormone levels in the follicular fluid. An ultrasonographic diagnostic instrument was used to measure the diameter of the follicles in order to categorize the follicles into three groups the following: 8 small follicles (from 1.0 to less than1.5 cm), 8 medium follicles (from 1.5 to less than 3.0 cm), and 8 large follicles (from 3.0 to 5.0 cm), respectively. The analysis of the follicular fluid in ovaries of estrous mares showed that the concentrations of androstenedione were significantly higher in the medium or large follicles than in the small follicles and the concentrations of estradiol-17β were significantly higher in larger follicles than in the small or medium follicles (P<0.05). The concentrations of progesterone and PGF_2α, on the other hand, did not significantly vary regardless of follicluar size. In the follicles within the mare ovaries that have had estrous stage, the concentrations of the hormones related the ovulation, namely androstenedione and estradiol-17β, were higher with larger follicles.     

犬不同生殖周期阶段卵巢的组织结构观察

为了探讨犬卵巢组织结构和生殖周期阶段的相关性,试验对犬不同生殖周期阶段卵巢的外观形态和组织结构进行观察。结果表明,犬卵泡期、黄体期和乏情期卵巢体积分别为812.63、1081.80和446.03 mm³,黄体期高于卵泡期和乏情期(P＜0.05),卵泡期高于乏情期(P＜0.05);卵泡期、黄体期和乏情期卵巢质量分别为0.89、1.14和0.71 g,卵泡期低于黄体期且高于乏情期,但3者之间不存在显著性差异(P＞0.05);卵泡期卵巢中可见较多次级卵泡和少量成熟卵泡,黄体期卵巢中可见部分次级卵泡和闭锁卵泡,并有大量黄体存在,乏情期卵巢中卵泡类型主要以原始卵泡为主。可见,犬卵巢形态及组织结构与所处生殖周期阶段有关。     

Follicular dynamics and colour Doppler vascularity evaluations of follicles and corpus luteum in relation to plasma progesterone during the oestrous cycle of Surti buffaloes

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.     

Ovarian follicular growth, function and turnover in cattle: a review

Studies in cattle assessing changes in number and size of antral follicles, concentrations of estradiol, androgens and progesterone in serum and follicular fluid, and numbers of gonadotropin receptors per follicle during repetitive estrous cycles and postpartum anestrus are reviewed. The rate of growth of small follicles (1 to 3 mm) into larger follicles increases as the estrous cycle progresses from d 1 to 18 (d 0 = estrus). Size of the largest antral follicle present on the ovary also increases with advancement of the estrous cycle. Most large follicles (greater than 10 mm) persist on the ovarian surface for 5 d or more between d 3 and 13 of the bovine estrous cycle. After d 13, most of these large follicles are replaced more frequently by new growing follicles (turnover) with an increased probability for recruitment of the ovulatory follicle after d 18. More research is needed to determine the time required for growth of bovine follicles from small to large antral size and evoke recruitment of the ovulatory follicle. Factors that regulate selection of the ovulatory follicle are unknown but may involve increased frequency of LH pulses in blood, altered blood flow and(or) changes in intrafollicular steroids and proteins. Quantitative evaluation of ovarian follicles indicated occurrence of consistent short-term changes in fluid estradiol and numbers of luteinizing hormone receptors in cells of large follicles only during the pre-ovulatory period. Presumably, low concentrations of follicular estradiol found during most of the estrous cycle are not due to a lack of aromatizable precursor or follicle-stimulating hormone receptors. Follicular fluid concentrations of progesterone increase only near the time of ovulation. Little is known about changes in follicular growth, turnover and function during postpartum anestrus in cattle. However, preliminary data suggest that the steroidogenic capacity of large follicles changes markedly during the postpartum period.     

Ovarian follicular populations and in vitro steroidogenesis on three different days of the bovine estrous cycle

This study was undertaken to determine changes in follicular populations on ovaries of dairy cows during three stages of the estrous cycle and their steroidogenic capacity in vitro. Numbers of small (2.0 to 5.0 mm), intermediate (5.1 to 10 mm) and large (greater than 10 mm) antral follicles on ovaries of multiparous cows and heifers (n = 31) in the early luteal (d 4), mid-luteal (d 12) and follicular phase (d 19) of the estrous cycle were determined (d 0 = estrus), and steroidogenic capacity of intermediate and large follicles was measured in vitro. Total number of follicles and number of small follicles were greatest (P less than .05) on d 19 compared with d 12, with numbers on d 4 not different from either d 12 or 19. Intermediate follicles were fewer (P less than .05) on d 19 compared with d 4 or 12. Numbers of large follicles did not change. The proportion of estrogen active (EA) follicles was greater (P less than .05) on d 19 compared with d 4 or 12. Accumulation of estradiol-17 beta (E) into culture medium by intermediate follicles decreased (P less than .05) with increasing days of the estrous cycle, while accumulation of progesterone (P) was greater on d 19. In large follicles, accumulation of E into culture medium was greatest (P less than .05) on d 19 and the lowest on d 12 (P less than .05). In summary, the proportion of EA follicles increases during the preovulatory period, and E production increases in large EA follicles.(ABSTRACT TRUNCATED AT 250 WORDS)