Histological and immunohistochemical characterization of equine anovulatory haemorrhagic follicles (AHFs).
Abstract: Anovulatory haemorrhagic follicles (AHFs) are often the reason for ovulation failure in the mare. As the underlying factors that lead to AHF development are not well understood, it was of interest to investigate the vascularization of AHFs compared with normal follicles and corpora lutea (controls). In the present study, the ovarian cell populations investigated immunohistochemically included granulosa and luteal cells as well as various vascular structures. None of these cell types showed differences in the expression of vascular endothelial growth factor A (VEGF-A) between control ovaries containing normal follicles and corpora lutea and ovaries with AHFs. In contrast, a considerable reduction in the proportion of Flk-1-expressing cells, together with a decreased intensity of staining, was apparent in the AHFs. This greatly reduced expression of Flk-1 in the luteinized cells and the vascular structures of AHFs may lead to a distinct decrease in the potential pro-angiogenic activity of VEGF-A in these structures compared with the situation in normal follicles and corpora lutea. Furthermore, the authors suspect that the distinct expression of angiopoietin2 and VEGF-A seen in the cells within the inner fibrous layers of the AHFs was caused by hypoxia resulting from deficient vascularization, as suggested by the irregularity of the capillaries present in the luteinized wall of the AHF. In addition, whereas LH-receptor (LH-R) expression occurred uniformly in all stages of development of the corpora lutea in normal control ovaries, there was highly variable labelling for LH-R in all the AHFs examined, thereby indicating a possible numerical deficiency of LH-receptors in AHFs. The authors concluded that, despite the apparent expression of sufficient VEGF-A in the AHFs allows ovulation and corpus luteum formation, a relative lack of receptor, Flk-1, effects the pro-angiogenic activity of VEGF-A which could be a reason for ovulation failure associated with AHF formation.
Publication Date: 2008-10-09 PubMed ID: 18954391DOI: 10.1111/j.1439-0531.2008.01085.xGoogle Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research article investigates the vascular structure of anovulatory haemorrhagic follicles (AHFs) in horses, which often result in ovulation failure. The study found a significant decrease in the expression of certain cell types in AHFs, which could influence the potential pro-angiogenic activity, potentially leading to ovulation failure.
Investigation of Ovarian Cell Populations
- The research was primarily focused on understanding the AHFs compared to normal ovarian follicles and corpora lutea (controls).
- Different cell populations within the ovaries, including granulosa and luteal cells, as well as various vascular structures, were investigated using immunohistochemical techniques.
- The researchers found no difference in the expression of the vascular endothelial growth factor A (VEGF-A), a key protein involved in blood vessel formati on, between control ovaries and those with AHFs.
Expression of Flk-1
- In contrast, the study revealed a significant decrease in the proportion of Flk-1-expressing cells in the AHFs, indicated by reduced staining intensity.
- Flk-1 is a protein receptor that binds VEGF-A, when expressed less, it reduces the potential pro-angiogenic activity, which could contribute to abnormal follicle function.
Hypoxia and Distinct Expression of Angiopoietin2 and VEGF-A
- The authors hypothesize that the distinct expression of angiopoietin2 and VEGF-A in AHFs may be a result of hypoxia caused by deficient vascularization, suggested by irregular capillaries in the luteinized wall of the AHF.
Expression of LH-Receptors
- The study also drew attention to the discrepancy in the expression of LH-receptors (LH-R) in the AHFs.
- While LH-R expression occurred uniformly at all stages of development in the corpora lutea of control ovaries, AHFs showed highly variable labelling for LH-R, indicating a possible deficiency of LH-receptors, which are critical for ovulation and luteinization.
Conclusion
- The authors concluded that while there’s sufficient expression of VEGF-A in AHFs, which theoretically should permit ovulation and corpus luteum formation, the relative lack of Flk-1 receptors affects the pro-angiogenic activity of VEGF-A, potentially resulting in ovulation failure associated with AHF formation.
Cite This Article
APA
Ellenberger C, Müller K, Schoon HA, Wilsher S, Allen WR.
(2008).
Histological and immunohistochemical characterization of equine anovulatory haemorrhagic follicles (AHFs).
Reprod Domest Anim, 44(3), 395-405.
https://doi.org/10.1111/j.1439-0531.2008.01085.x Publication
Researcher Affiliations
- Institute of Pathology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 33, Leipzig, Germany. ellen-ber@rz.uni-leipzig.de
MeSH Terms
- Angiopoietin-2 / analysis
- Animals
- Anovulation / metabolism
- Anovulation / pathology
- Anovulation / veterinary
- Capillaries / pathology
- Corpus Luteum / blood supply
- Corpus Luteum / chemistry
- Corpus Luteum / pathology
- Female
- Hemorrhage / metabolism
- Hemorrhage / pathology
- Hemorrhage / veterinary
- Horse Diseases / metabolism
- Horse Diseases / pathology
- Horses
- Immunohistochemistry
- Luteinization
- Ovarian Diseases / metabolism
- Ovarian Diseases / pathology
- Ovarian Diseases / veterinary
- Ovarian Follicle / blood supply
- Ovarian Follicle / chemistry
- Ovarian Follicle / pathology
- Receptors, LH / analysis
- Vascular Endothelial Growth Factor A / analysis
- Vascular Endothelial Growth Factor Receptor-2 / analysis
Citations
This article has been cited 2 times.- Ranjbaran A, Nejabati HR, Ghasemnejad T, Latifi Z, Hamdi K, Hajipour H, Raffel N, Bahrami-Asl Z, Hakimi P, Mihanfar A, Nouri M, Fattahi A. Follicular Fluid Levels of Adrenomedullin 2, Vascular Endothelial Growth Factor and its Soluble Receptors Are Associated with Ovarian Response During ART Cycles.. Geburtshilfe Frauenheilkd 2019 Jan;79(1):86-93.
- Ishak GM, Bashir ST, Dutra GA, Gastal GDA, Gastal MO, Cavinder CA, Feugang JM, Gastal EL. In vivo antral follicle wall biopsy: a new research technique to study ovarian function at the cellular and molecular levels.. Reprod Biol Endocrinol 2018 Jul 28;16(1):71.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
