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Title: A histological study of angiogenesis and cell death in the equine corpus luteum
Author: Alzi'abi, O.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2002
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Angiogenesis is a dynamic process of endothelial cell proliferation and microvessel formation regulated by the production of angiogenic factors, especially VEGF. It was established that the early luteal phase was associated with intense endothelial cell proliferation, expression of VEGF and the growth of the microvascular network. Angiogenesis continued during the mid-luteal phase by at a reduced level. However, VEGF remained high and the full microvasculature had been established for optimal progesterone secretion. During regression, endothelial cell proliferation and VEGF expression declined, with a reduction in vascularity and a marked progesterone decline. The combination of TUNEL immunostaining and ultrastructural examination provided definitive identification of the types of cell death involved in the CL. It was demonstrated that apoptotic and non-apoptotic mechanisms were involved in the demise of the CL. The presence of fragmented chromatin, pyknotic cells, round dense bodies and phagocytosis were considered as apoptotic features. Other changes (crenation of the nuclear membrane with shrinkage of the nucleus) seen in some luteal cells indicated there is an additional non-apoptotic form of cell death at luteolysis. TNFa, NO and bFGF immunostaining in the luteal cells during the luteal phase may indicate a paracrine and/or autocrine role for these factors in the CL and may play a role in luteal development and regression. This thesis has described for the first time the cellular changes of angiogenesis and regression post PGF-induced regression. The findings revealed massive neutrophils and vasodilation as well as a similar pattern of other cellular changes to those undergone during natural luteolysis. This study increases our understanding of equine CL control. It demonstrates that luteal angiogenesis is important for luteal function and it is likely that VEGF is essential for luteal angiogenesis. Luteolysis and cell death play a crucial role in ovarian cyclicity and the demise of luteal tissue represents both apoptotic and non-apoptotic pathways.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available