Emergence Of Dominant Follicle Research Articles

Clinical monitoring of serum sex hormones during normal menstrual follicle growth cycle

Objective To study the changes of six sex hormones corresponding to the follicle growth during the normal menstrual cycle of Chinese women. Methods Thirty Chinese women with regular menstrual period and average age of (28.8±3.2) years were selected for the study by Peking Union Medical College Hospital in September, 2010. Growth of follicles was monitored by using transvaginal sonography. Six sex hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), progesterone (P), testosterone (T), and prolactin (PRL) were measured by chemoluminescence immunoassay every day during a menstrual cycle. Nonparametric statistical analysis was used. Results Menstrual cycle of all the patients was in the range of 25 to 39 d, with mean of (29.5 ± 3.1) d. Length of follicular phase and luteal phase was 15.3 and 14.4 d, respectively.Number of days from antral follicle to emergence of dominant follicle, and from the latter to ovulation, was 6.2 and 8.9 d, respectively. Average diameter of preovulatory follicle was 19.33 mm. Both FSH and LH reached peak on the day before ovulation. P started to increase before ovulation and remained at a high plateau from 6th to 9th day after ovulation. Both PRL and T reached peak after ovulation, near the end of a menstrual cycle. Conclusions A small rise of LH and P emerges just 1 to 2 d before ovulation, indicating the maturing of follicle. PRL and T shows cyclic changes as follicle grows. Therefore, PRL and T levels should be measured in the early follicle phases in the clinical practice so that leading the impact of menstrual cycle minimal.(Chin J Lab Med, 2017, 40: 169-173) Key words: Menstrual cycle; Ovarian follicle; Gonadal steroid hormones; Luminescent measurements; Immunoassay

Postpartum follicular and luteal activity in Holstein-Friesian cows genetically selected for high or low mature bodyweight: Relationships with follicle stimulating hormone, insulin, insulin-like growth factor-1 and growth hormone

AIM: To investigate ovarian follicular and luteal activity during the postpartum period of cows genetically selected for high or low mature bodyweight, in relation to metabolic and reproductive endocrine parameters, to determine whether there are differences between strains that could affect fertility outcomes. METHODS: The presence of follicles ≥5 mm diameter and luteal structures was mapped in the ovaries of 12 high (heavystrain) and 12 low (light-strain) mature bodyweight cows by daily trans-rectal ultrasonography from Day 7 postpartum until the end of their first normal oestrous cycle. Blood samples were collected daily, for measurement of concentrations of follicle stimulating hormone (FSH), progesterone, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and insulin. Intervals to first ovulation were calculated from ultrasonography data. RESULTS: Heavy-strain cows had shorter intervals than light-strain cows from calving to the emergence of the first (9.0 (SE 0.9) vs 12.4 (SE 1.3) days) and second (16.4 (SE 1.8) vs 20.6 (SE 1.6) days) dominant follicles (p<0.05). Concentrations of FSH in heavy-strain cows prior to the emergence of the second, third and fourth dominant follicles were higher than in light-strain cows (p<0.05). Heavy-strain cows were more likely to have a large (>15 mm diameter) follicle earlier than light-strain cows (p<0.01). Concentrations of insulin and IGF-1, but not those of GH, were higher in heavy- than light-strain cows during the postpartum period (p=0.01 and p=0.02, respectively), and concentrations of both on Day 6 were inversely related to the time of emergence of the first dominant follicle (p>0.01). Concentrations of progesterone were similar in both strains of cow until Day 10 of the first oestrous cycle, but thereafter were higher in light- than heavy-strain cows until Day 16. Progesterone concentrations in heavy-strain cows declined earlier and more rapidly than in their lighter counterparts. CONCLUSION: These results indicate that there is a rapid postpartum resumption of follicular activity in both heavy-and light-strain cows, but that there is an earlier emergence of dominant follicles and ovulation in the former. Differences in luteal function, in terms of lower dioestrus progesterone concentrations and an earlier onset of luteolysis, in heavy- than light-strain cows might be sufficient to impair the fertility of the former.

Selective expression of insulin-like growth factor system components during porcine ovary follicular selection.

In situ hybridization was used to map anatomical patterns of insulin-like growth factor (IGF) system gene expression in the gilt ovary through the estrous cycle. IGF-I, IGF-II< and IGF-I receptor messenger RNAs (mRNAs) were coexpressed in granulosa cells of developing and dominant follicles through the follicular phase. IGF-I and IGF-I receptor mRNAs were selectively concentrated in healthy follicles, whereas IGF-II mRNA was found in all follicles regardless of incipient or overt atresia. IGF-binding protein-1 (IGFBP-1) was not detected in the gilt ovary at any stage. IGFBP-2 mRNA was most abundant in granulosa cells of small follicles and in the ovarian vasculature regardless of cycle stage. IGFBP-2 mRNA persisted in granulosa cells of preovulatory follicles and corpora lutea. IGFBP-3 mRNA was not detected in developing follicles, but was detected in all luteal phase corpora lutea, apparently expressed by theca lutein cells. IGFBP-4 demonstrated a highly dynamic pattern of gene expression, closely tracking LH receptor gene expression throughout the follicular and luteal phases of the estrous cycle. IGFBP-4 mRNA was concentrated in the theca of medium to large growing follicles, but was not detected in granulosa cells until the emergence of dominant follicles in the late follicular stage, when the granulosa cells showed morphological evidence of luteinization as well as LH receptor gene expression. IGFBP-4 mRNA expression continued in granulosa cells of corpora lutea during the luteal phase and was not detected in atretic follicles. IGFBP-5 mRNA was concentrated in the surface or germinal epithelium and in capillary endothelium, particularly in capillaries of corpora lutea. In summary, there is selective expression of IGF-I, IGF-I receptor, and IGFBP-2 and -4 mRNAs during the process of follicular selection in the gilt ovary, with IGFBP-4 expression being closely associated with follicular selection and luteinization. These observations support an important role for autocrine/paracrine IGF action modulated by IGFBP-2 and -4 in both follicular growth and differentiation in the porcine ovary.

Ovarian Follicular Waves in Dairy Cows After Administration of Gonadotropin-Releasing Hormone at Estrus

A crossover design experiment was conducted to examine the effects of GnRH on hormonal concentrations and changes in ovarian structures of lactating dairy cows during the estrous cycle. Cows were assigned randomly to receive either 100μg of GnRH or saline 12h after estrus (d 0) was first observed. Ultrasonographic examinations of the ovaries performed daily throughout the estrous cycle detected either three (n = 7) or four (n = 6) follicular waves. Transient increases in FSH generally preceding the follicular wave containing the dominant (preovulatory) follicle, and the emergence of the dominant follicle before the subsequent estrus occurred later in GnRH-treated than in saline-treated cows with either three or four follicular waves. Day of emergence of dominant follicles within follicular waves was preceded 83% of the time by a transient increase in FSH and was followed consistently by increased serum estradiol-17β which generally reached peak concentrations concomitant with the peak diameter of the dominant follicle. Although clearly defined pulses were detected in 19 out of 26 sampling periods on d 7 and 14, number of FSH pulses and percentage of cows with pulses of FSH were similar in GnRH-treated and saline-treated cows with three or four follicular waves. In conclusion, treatment of cows with GnRH 12h after the onset of estrus delayed the appearance of the next ovulatory follicle in cows with either three or four follicular waves. Regardless of treatment, emergence of dominant follicles was preceded in most cases by a transient increase in FSH and followed consistently by increased estradiol-17β.