Ovaries were studied on luteal days 10, 18 and 22 (corresponding to the mid luteal phase, functional luteal regression and structural luteal regression respectively), and also 12 and 24 hours after administration of either PGF2a or GnRH antagonist. Decreased progesterone concentrations indicative of functional luteal regression were apparent 12 hours later. Analysis of haematoxylin and eosin stained sections of corpora lutea indicated that the administration of PGF2a or GnRH antagonist resulted in apoptosis, and also in the formation of cytoplasmic vacuoles in steroidogenic cells. Apoptosis in corpora lutea was further investigated by 3' end labelling DNA extracted from corpora lutea, and by <i>in situ</i> 3' end labelling of sections of ovarian tissue. Apoptosis was found to occur after induced luteolysis and in naturally regressing corpora lutea but only after progesterone had decreased to follicular phase values. Therefore the decline in progesterone characteristic of functional luteal regression was not caused by the apoptotic cell death of steroidogenic cells. However, apoptosis played a role in structural luteal regression. Ubiquitin is expressed only by live cells undergoing a process of non-apoptotic cell death. Ubiquitin expression was only found in PGF2a, but not in GnRH antagonist treated luteal tissue, suggesting three possible explanations: that the cells in GnRH antagonist treated animals were dead prior to the collection point of 12 hours, or that the cells were not in a cell death pathway, or that cell death was occurring via different mechanisms in PGF2a and GnRH antagonist treated animals. The importance of the vasculature in luteal regression was investigated by labelling endothelial cells with an antibody against von Willebrand Factor VIII Antigen. Endothelial cell numbers remained constant after administration of luteolytic agents, indicating that induced luteal regression was not effected by vascular changes. Similarly, the vascualture did not change during functional regression in untreated animals. Vascular remodelling, however, occurred during structural luteal regression, when the vasculature changed from an extensive network of small capillaries to a system comprised of a lower number of larger blood vessels.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:664152 |
| Date | January 2000 |
| Creators | Young, Fiona Margaret |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/23277 |
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