Histomorphological and immunohistochemical study of angiogenesis and angiogenic factors in the ovary of the mare.

This research paper focuses on the study of blood vessel formation (angiogenesis) and the role of specific growth factors in the ovaries of mares. The findings suggest that the coexpression of these factors is most intense during the ovulatory period, indicating their significance in the maturation of tertiary follicles and the endocrine function of the Corpus luteum in the mare’s ovary.

Understanding the Research Scope and Methodology

• The researchers studied cyclical ovaries from 18 mares using histological and immunohistochemical examination.
• The focus was on several factors and receptors associated with angiogenesis, including Vascular Endothelial Growth Factor A and B (VEGF A; VEGF B), Angiopoietin 1 and 2 (Ang1; Ang2), Vascular Endothelial Growth Factor Receptor 1 and 2 (VEGF-R1; VEGF-R2), the Angiopoietin receptor (Tie2), and von Willebrand factor.

Role of Angiogenic Factors and Receptors during Ovulation

• During the periovulatory period, a distinct process of angiogenesis occurs which is critical for tertiary follicle maturation and for the Corpus luteum’s endocrine function.
• The co-expression of the investigated factors and receptors was most intense during this period, signifying their importance in these processes.
• Particularly, VEGF A, Ang2, VEGF-R2, and Tie2 seemingly have a crucial role in angiogenesis during the development of follicles and luteal in the mare’s ovary.
• Conversely, Ang1 appears to support vessel stabilisation, promoting structural integrity of the blood vessels.

Influence of Angiogenic Factors during Luteal Regression and Follicular Atresia

• Luteal regression and follicular atresia are processes leading to a decrease in the size of the luteal tissue and the death of ovarian follicles, respectively.
• Research findings suggest that in the absence of VEGF A, Ang2 and its receptor Tie2 contribute significantly to these processes by helping in vessel regression. This implies that these factors play a key role in both luteolysis (degradation of the Corpus luteum) and follicular atresia.
• Therefore, these findings may provide valuable insights into the mechanisms of ovarian development and maturation in mares, aiding future research in equine reproduction and fertility.