Hormonal mechanisms regulating follicular wave dynamics II: Progesterone decreases diameter at follicle selection regardless of whether circulating FSH or LH are decreased or elevated

Systemic administration of ovulation-inducing factor (OIF), discovered recently in seminal plasma of llamas, alpacas (induced ovulators), and cattle (spontaneous ovulators), stimulated ovulation in >90% of female llamas and alpacas. The objective of the present study was to test the hypothesis that purified OIF from llama seminal plasma would induce ovulation in cattle. Peripubertal heifers, weighing 323 � 27 kg, were used to minimize the confounding effect of spontaneous ovulation. Heifers (n = 11/group) were treated intramuscularly with 1.0 mg/100 kg of purified OIF, 100 µg of GnRH (positive control), or 2.5 mL of phosphate-buffered saline (negative control). Ovarian dynamics were monitored daily by transrectal ultrasonography for 10 days post-treatment. Blood samples were collected at 0.5- to 1-h intervals for 8 h, beginning at the time of treatment. Ovulation occurred in 9/11 (82%) of GnRH-treated heifers and in 1/11 (9%) heifers in each of the OIF- and saline-treated groups (P < 0.05). A surge in plasma LH concentration was detected within 30 min of treatment in the GnRH group (2.2 � 0.1 ng mL–1; P < 0.05), but remained at the basal level in the OIF- and saline-treated groups (0.3 � 0.1 and 0.2 � 0.1 ng mL–1, respectively). The onset of regression of the dominant follicle present at the time of treatment was earlier (P < 0.05) in OIF- v. saline-treated heifers (3.1 � 0.6 days v. 6.0 � 0.7 days). The interval from treatment to follicular wave emergence was shorter (P < 0.05) in GnRH- and OIF-treated heifers than in those treated with saline (1.1 � 0.4 days, 1.5 � 0.3 days, and 3.1 � 0.3 days, respectively). A similar pattern was observed for emergence of the second follicular wave (5.1 � 0.7 days, 4.6 � 0.5 days, and 6.6 � 0.4 days, respectively). Purified OIF did not induce ovulation in heifers but hastened both the regression of the extant dominant follicle and follicular wave emergence. Results provide a rationale for the hypothesis that OIF from seminal plasma is involved in controlling follicular wave dynamics in spontaneously ovulating species (e.g., Bos taurus) through a suppressive effect on the dominant follicle. The mechanism of action on ovarian follicular wave dynamics, as well as species specificity, remains to be elucidated.

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THE EFFECTS OF DAILY INJECTIONS OF oFSH BETWEEN TWO ENDOGENOUS FSH PEAKS ON FOLLICULAR WAVE DYNAMICS IN ANESTROUS EWES

Biology of Reproduction ◽

10.1093/biolreprod/77.s1.222c ◽

2007 ◽

Vol 77 (Suppl_1) ◽

pp. 222-223

Author(s):

Behzad Toosi ◽

Ashley Ziegler ◽

Srinivas Seekallu ◽

David Barrett ◽

Norman Rawlings

Keyword(s):

Wave Dynamics ◽

Follicular Wave

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The evolution of improved and simplified superovulation protocols in cattle

Reproduction Fertility and Development ◽

10.1071/rd11919 ◽

2012 ◽

Vol 24 (1) ◽

pp. 278 ◽

Cited By ~ 24

Author(s):

Reuben J. Mapletoft ◽

Gabriel A. Bó

Keyword(s):

Embryo Transfer ◽

Treatment Protocol ◽

Bovine Embryo ◽

Treatment Protocols ◽

Wave Dynamics ◽

Follicular Wave ◽

Recent Treatment ◽

Gonadotrophin Releasing Hormone ◽

Animal Handling ◽

On Farm

Superovulation protocols have improved greatly since the early days of bovine embryo transfer when purified gonadotrophins were not available, follicular wave dynamics were unknown physiological phenomena and prostaglandins were not available. Although superstimulatory protocols in cattle are normally initiated mid-cycle, elective control of follicular wave emergence and ovulation have had a great impact on the application of on-farm embryo transfer. However, the most common treatment for the synchronisation of follicular wave emergence involves the use of oestradiol, which cannot be used in many parts of the world. Therefore, the need for alternative treatments has driven recent research. An approach that has shown promise is to initiate follicle-stimulating hormone (FSH) treatments at the time of the emergence of the new follicular wave following ovulation induced by gonadotrophin-releasing hormone. Alternatively, it has been shown that it may be possible to ignore follicular wave status and, by extending the treatment protocol, induce subordinate follicles to superovulate. Finally, the short half-life of pituitary FSH necessitates twice-daily treatments, which are time-consuming, stressful and subject to error. Recent treatment protocols have permitted superstimulation with a single FSH treatment or two treatments 48 h apart, reducing the need for animal handling during gonadotrophin treatments.

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Follicular wave dynamics and Growth factors gene expression in Braford heifers

Anatomia Histologia Embryologia ◽

10.1111/ahe.12587 ◽

2020 ◽

Vol 49 (6) ◽

pp. 820-829

Author(s):

Pablo Sebastián Reineri ◽

María Sumampa Coria ◽

Santiago Callejas ◽

Gustavo Adolfo Palma

Keyword(s):

Gene Expression ◽

Growth Factors ◽

Wave Dynamics ◽

Follicular Wave

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Identification of novel genes associated with dominant follicle development in cattle

Reproduction Fertility and Development ◽

10.1071/rd07102 ◽

2007 ◽

Vol 19 (8) ◽

pp. 967 ◽

Cited By ~ 15

Author(s):

Anna E. Zielak ◽

Niamh Forde ◽

Stephan D. E. Park ◽

Fiona Doohan ◽

Paul M. Coussens ◽

...

Keyword(s):

Cell Differentiation ◽

Follicular Development ◽

Intracellular Signalling ◽

Follicle Development ◽

The Novel ◽

Dominant Follicle ◽

Novel Genes ◽

Follicular Wave ◽

New Genes ◽

Follicle Selection

Follicle development is regulated by the interaction of endocrine and intrafollicular factors, as well as by numerous intracellular pathways, which involves the transcription of new genes, although not all are known. The aim of the present study was to determine the expression of a set of unknown genes identified by bovine cDNA microarray analysis in theca and granulosa cells of dominant and subordinate follicles, collected at a single stage of the first follicular wave using quantitative real-time polymerase chain reaction. Differences were further examined at three stages of the follicular wave (emergence, selection and dominance) and bioinformatics tools were used to identify these originally unknown sequences. The suggested name function and proposed role for the novel genes identified are as follows: MRPL41 and VDAC2, involved in apoptosis (dominant follicle development); TBC1D1 stimulates cell differentiation (growth associated with dominant follicle selection and development); STX7, promotes phagocytosis of cells (subordinate follicle regression); and SPC22 and EHD3, intracellular signalling (subordinate follicle regression). In conclusion, we have identified six novel genes that have not been described previously in ovarian follicles that are dynamically regulated during dominant follicle development and presumably help mediate intracellular signalling, cell differentiation, apoptosis and phagocytosis, events critical to follicular development.

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Control of ovarian follicular wave dynamics in cattle: Implications for synchronization & superstimulation

Theriogenology ◽

10.1016/s0093-691x(05)80044-5 ◽

1994 ◽

Vol 41 (1) ◽

pp. 19-24 ◽

Cited By ~ 88

Author(s):

G.P. Adams

Keyword(s):

Wave Dynamics ◽

Follicular Wave

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Follicle selection in cattle and horses: role of intrafollicular factors

Reproduction ◽

10.1530/rep.1.01233 ◽

2006 ◽

Vol 132 (3) ◽

pp. 365-377 ◽

Cited By ~ 107

Author(s):

M A Beg ◽

O J Ginther

Keyword(s):

The Other ◽

Dominant Follicle ◽

Follicular Wave ◽

Igf System ◽

Igf I ◽

The Future ◽

Igf Binding ◽

Preparatory Stage ◽

Igf Binding Protein ◽

Follicle Selection

The eminent event in follicle selection during a follicular wave in monovular species is diameter deviation, wherein one follicle continues to grow (developing dominant) and other follicles (subordinates) begin to regress. In cattle, the IGF system, oestradiol and LH receptors are involved in the intrafollicular events initiating deviation as indicated by the following: (1) concentrations of free IGF-I and oestradiol in the follicular fluid and number of LH receptors in the follicular wall increase more dramatically in the future dominant follicle than in the future subordinate follicles before the beginning of deviation and (2) ablation of the largest follicle (LF) or injection of recombinant human IGF (rhIGF)-I into the second LF at the expected beginning of deviation increases the concentrations of oestradiol in second LF before the expected beginning of deviation between second LF and third LF. In horses, an increase in free IGF-I, oestradiol, inhibin-A and activin-A is greater in the future dominant follicle than in other follicles before the beginning of deviation. However, free IGF-I is the only one of these four factors needed for the initiation of deviation in horses as indicated by the following: (1) ablation of LF at the expected beginning of deviation increases the concentrations of free IGF-I in second LF before the beginning of deviation between second LF and third LF but does not increase the other factors; (2) injection of rhIGF-I into second LF at the expected beginning of deviation causes second LF to continue to grow and become a codominant follicle and (3) injection of IGF-binding protein-3 into LF at the expected beginning of deviation causes LF to regress and second LF to become dominant. Thus, the dramatic changes in the IGF system in LF compared to other follicles before the beginning of deviation play a crucial role in the events that lead to the beginning of diameter deviation in both cattle and horses. Oestradiol and LH receptors also play a role in cattle. These intrafollicular events prepare the selected follicle for the decreasing availability of FSH and increasing availability of LH. The other follicles of the wave have the same future capability but do not have adequate time to attain a similar preparatory stage.

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203.Studies of the activin pathway in dominant and subordinate bovine follicles before, during and after selection

Reproduction Fertility and Development ◽

10.1071/srb04abs203 ◽

2004 ◽

Vol 16 (9) ◽

pp. 203

Author(s):

B. C. Sisco ◽

A. N. Shelling ◽

P. L. Pfeffer

Keyword(s):

Feedback Loop ◽

Mrna Levels ◽

Dominant Follicle ◽

Rt Pcr ◽

Protein Levels ◽

Follicular Wave ◽

Follicular Size ◽

Quantitative Changes ◽

Follicle Selection ◽

Inhibin Subunits

In monovulatory species such as cattle, one of a cohort of developing follicles assumes dominancy and continues to grow in each follicular wave. After dominant follicle selection, pituitary-derived FSH levels decrease through a negative feedback loop mediated by oestradiol and inhibin A produced by the dominant follicle. The dominant follicle itself only requires very low basal levels of FSH, thus escaping atresia which is the fate of the subordinate follicles. The mechanisms involved in dominant follicle (DF) selection remain unclear. Most studies have focused on the stages following selection. To investigate what roles activin and inhibin play in DF selection we looked at the quantitative changes in the expression of the genes coding for the activin/inhibin subunits (Inhibin α, βA and βB) as well as other genes in the activin pathway (SMAD2, ActRIIA/B, follistatin (FST), FSHR). We examined mRNA levels in follicular granulosa cells (GCs) before (d1.5), during (d2.5) and after (d3.5 and 7) DF selection using real-time RT-PCR. Prior to DF selection, highest levels of inhibin βA, FST and SMAD2 transcripts converged on the largest follicles. Inhibin α, ActRIIA/B and FSHR levels did not correlate with follicular size at this stage. At Day 2.5, highest levels of inhibin βA, inhibin α, FST and SMAD2 transcripts were seen in a single putative DF. ActRIIA/B and FSHR did not show any difference between follicles. By Days 3.5 and 7, a dramatic difference in expression levels of inhibin βA, inhibin α and FST were seen in DF compared to SF. Yet in absolute terms inhibin βA levels decreased after selection, whereas inhibin α levels increased. Inhibin βB expression was only detected in Day 7 GCs and was significantly higher in the DF. These results suggest a shift from an activin environment during the pre and peri-DF selection period, to an inhibin environment following DF selection. Inhibin/activin protein levels in the follicular fluid using western ligand blotting confirmed this. We postulate that the higher activin activity within DF influences the selection mechanism as activin and inhibin have been shown to play a role in gonadotropin regulation in the ovary around the time of selection.

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