Temporal Expression of Angiogenic Factors in Granulosa and Theca Cells of Developing Porcine Preovulatory Follicles and the Potential Involvement of Angiogenin in the Luteinizing Follicle.
Bibliographic record
Abstract
Nutritional restriction and increased catabolism during lactation in primiparous sows has been associated with changes in follicle and oocyte quality and can be detrimental to embryonic survival and development in the subsequent litter. Delaying breeding of primiparous sows until the second oestrus after weaning resulted in increased embryonic survival and litter size and greater preovulatory follicle maturity. Understanding the molecular mechanisms underlying such differences is of considerable practical significance. Our previous work failed to establish a role for the transforming growth factor β superfamily in mediating these differences in follicle maturity and embryonic survival. However, our results showed that angiogenic factors represent a large component of the factors secreted by the granulosa and theca cells. Therefore, the aims of the present study were to investigate the temporal expression of the angiogenic factors HIF1A, VEGFA, ANGPT1, ANGPT2, ANG, FLT1, KDR and TEK in the granulosa and theca cells of developing porcine follicles and to determine if they could play a role in creating the differences in preovulatory follicle characteristics and embryo survival associated with the first vs. second post-weaning oestrus in primiparous sows. Granulosa and theca cells were recovered by dissection from antral follicles (2-10 mm in diameter) obtained from first parity sows at day 1, 2 and 4 after weaning and at day 14, 16 and 20 of their subsequent estrous cycle. These time points correspond to the recruitment of a growing cohort of follicles, the mid-selection phase and the final selection of the pre-ovulatory follicle population. Oviduct and uterine samples were also collected from these animals. Plasma estrogen and progesterone analysis was used to confirm the physiological status of each animal and follicular fluid estradiol concentration in day 4 and day 20 animals was also used to determine whether preovulatory follicles had been exposed to the LH surge. Total RNA was extracted, reverse transcribed and gene expression was determined by Q- PCR. The ΔCt values were calculated using cyclophilin as the endogenous reference genes and the data were analysed using the general linear model procedure of SAS (SAS Institute Inc., Cary, NC). Changes in ANGPT1, ANGPT2 and VEGFA mRNA abundance in granulosa and theca cells suggest an involvement of these genes in the selection and maintenance of the preovulatory follicle population. HIF1A mRNA abundance positively correlated with the expression of several angiogenic genes, suggesting that regulation of this transcription factor may also be important for the development of adequate vasculature. In addition, ANG mRNA abundance was higher in the theca cells isolated during the final follicle selection phase following the preovulatory LH surge of the 2nd compared to the 1st wave of follicular development. We hypothesized that increased ANG expression leads to increased vascularity in the preovulatory follicle and in the early corpora lutea. In turn, this would lead to an earlier rise in progesterone allowing a more efficient priming of the oviduct environment thereby favouring early embryo development. Differences in ESR2 and PTGFR mRNA expression observed in the oviduct of these animals appear to support our hypothesis. In conclusion, our results clearly demonstrate the presence of a complex angiogenic system within the pig ovarian follicle that could ultimately affect embryonic survival. (poster)
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".