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Calcium signals and the activation of embryo development in mice and humans

Sanusi, Randa 2016. Calcium signals and the activation of embryo development in mice and humans. PhD Thesis, Cardiff University.
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Abstract

During fertilisation the egg undergoes a series of remarkable activation events including a prolonged series of intracellular Ca2+ oscillations. The Ca2+ oscillations are necessary and sufficient to trigger egg activation and support pre-implantation embryo development. The mechanism of the signal trigger is well established and involves a sperm factor released into the egg upon gamete fusion. Phospholipase C zeta (PLCζ) appears to be the mammalian sperm factor responsible for triggering Ca2+ oscillations during fertilisation. Consistent with this idea it has been found that, some cases of male factor infertility have been attributed to either qualitative or quantitative deficiencies in PLCζ. Intra-cytoplasmic sperm injection (ICSI) has overcome many cases of male factor infertility. However, some ICSI cases still see partial or total fertilisation failure. To overcome such failures, artificial egg activation using various protocols has been introduced. Ionophores are the main agents used to trigger artificial egg activation in human eggs. The work in this thesis provides evidence that the human PLCζ protein is effective and more efficient in triggering egg activation and in supporting pre-implantation embryo development in mouse eggs than other activators. That was achieved via a direct comparison of various activation protocols in a mouse model of ICSI fertilization failure. Furthermore through the use of ICSI and Ca2+ measurements in mouse eggs my studies have provided further evidence that the number of Ca2+ transients during activation can influence development to the blastocyst stage. Moreover, my work also investigates what methods could be used for injecting PLCζ protein within a clinic setting. . Other work has attempted to investigate how Ca2+ oscillations during fertilisation may influence later embryo development by testing the use of probe of hydrogen peroxide in mouse eggs. Overall the studies provide an important step in the development of new therapies for treating patients having problems conceiving with ICSI treatment.

Item Type: Thesis (PhD)
Date Type: Publication
Status: Unpublished
Schools: Medicine
Subjects: R Medicine > R Medicine (General)
Date of First Compliant Deposit: 5 December 2016
Last Modified: 03 Jan 2019 02:30
URI: http://orca-mwe.cf.ac.uk/id/eprint/96636

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